A006720
Somos-4 sequence: $a(0)=a(1)=a(2)=a(3)=1$; for $n \geq 4$, $a(n)=(a(n-1)a(n-3)+a(n-2)^2)/a(n-4)$.1, 1, 1, 1, 2, 3, 7, 23, 59, 314, 1529, 8209, 83313, 620297, 7869898, 126742987, 1687054711, 47301104551, 1123424582771, 32606721084786, 1662315215971057, 61958046554226593, 4257998884448335457, 334806306946199122193, ...
You're reading: Posts Tagged: oeis
- From Bracket 1: A002210, the decimal expansion of Khintchine’s constant.
- From Bracket 2: A001220, the Wieferich primes.
- From Bracket 3: A001462, Golomb’s sequence.
- From Bracket 4: A023811, the largest metadromes in base $n$.
- From the first round of reviews, we picked the one whose score we fiddled the least: A010727, all the 7s.
- And the wildcard is A058883, the wild numbers.
Integer Sequence Review Mêlée Hyper-Battle DX 2000, THE GRAND FINALE
Welcome to the Field of Dreams. Talking of which: why can’t you grow wheat in $\mathbb{Z}/6\mathbb{Z}$?
Anyway, we’re finally here: the Grand Finale of our tournament to find the Integest Sequence 2013. Here’s a reminder of the sequences vying for the title:
It’s a been a long, hard battle. We’ve seen some good sequences, some bad sequences, and an awful lot of plagiarised GIFs. So, without further ado, it’s time to start the
Integer Sequence Review Mêlée Hyper-Battle DX 2000 (Bracket 4)
Last week, A001462 – Golomb’s sequence – booked its place in the final. In retaliation for last week’s palaver, this week Christian has picked all the sequences. Unfortunately, the British Summer is happening today so we’re failing a bit, intellectually.
With that in mind, it’s time for round 4 of…
Here are the rules: we’re judging each sequence on four axes: Aesthetics, Completeness, Explicability, and Novelty. We’re reviewing six sequences each week for four weeks, picking a winner from each. Then, we’ll pick one sequence from the ones we reviewed individually before this thing started, plus a wildcard. Finally, a single sequence will be crowned the Integest Sequence 2013!
Integer Sequence Review Mêlée Hyper-Battle DX 2000 (Bracket 3)
Last week, A001220 – the Wieferich primes – booked its place in the final. This week, David has picked six sequences all on his own to form Bracket 3 of…
Here are the rules: we’re judging each sequence on four axes: Aesthetics, Completeness, Explicability, and Novelty. We’re reviewing six sequences each week for four weeks, picking a winner from each. Then, we’ll pick one sequence from the ones we reviewed individually before this thing started, plus a wildcard. Finally, a single sequence will be crowned the Integest Sequence 2013!
Integer Sequence Review Mêlée Hyper-Battle DX 2000 (Bracket 2)
Last week A002210, the decimal expansion of Khintchine’s constant, emerged victorious from Bracket 1. Now, get ready for round 2 of…
Here are the rules: we’re judging each sequence on four axes: Aesthetics, Completeness, Explicability, and Novelty. We’re reviewing six sequences each week for four weeks, picking a winner from each. Then, we’ll pick one sequence from the ones we reviewed individually before this thing started, plus a wildcard. Finally, a single sequence will be crowned the Integest Sequence 2013!
Integer Sequence Review Mêlée Hyper-Battle DX 2000 (Bracket 1)
After taking a couple of weeks off from reviewing integer sequences, we’ve decided to shake up the format. Prepare yourself for…
We’re going to review six sequences each week for four weeks, picking a winner from each. Then, we’ll pick one sequence from the ones we’ve already reviewed individually, plus a wildcard. Finally, a single sequence will be crowned the Integest Sequence 2013!
We’re still judging each sequence on four axes: Aesthetics, Completeness, Explicability, and Novelty.
Without further ado, here we go!
Integer Sequence Review: A052486
The Online Encyclopedia of Integer Sequences contains over 200,000 sequences. It contains classics, curios, thousands of derivatives entered purely for completeness’s sake, short sequences whose completion would be a huge mathematical achievement, and some entries which are just downright silly.
For a lark, David and I have decided to review some of the Encyclopedia’s sequences. We’re rating sequences on four axes: Novelty, Aesthetics, Explicability and Completeness.
Following last week’s palaver, we’re going to do our best to be serious this time. Game faces on.
A052486
Achilles numbers – powerful but imperfect: writing n=product(p_i^e_i) then none of the e_i=1 (i.e. powerful(1)) but the highest common factor of the e_i>1 is 1 (so not perfect powers).72, 108, 200, 288, 392, 432, 500, 648, 675, 800, 864, 968, 972, 1125, 1152, 1323, 1352, 1372, 1568, 1800, 1944, 2000, 2312, 2592, 2700, 2888, 3087, 3200, 3267, 3456, 3528, 3872, 3888, 4000, 4232, 4500, 4563, 4608, 5000, 5292, 5324, 5400, 5408, 5488, ...