#oeis

[kneadingmaths]

Happy new year! Hypergraphs are a generalization of graphs; trying to count hyperforests without seeds (i.e. without isolated nodes) leads to this integer sequence, containing 2026...

[mingarmat]

1/23

[sqrt-73]

Interesting math fact of the day #102:

2000020^64 + 1 is prime

[boredphysicsstudent]

A fun thing I found on the OEIS (online encyclopedia of integer sequences):

Suppose you have a sequence like

1,2,2,3,3,3,4,4,4,4…

The pattern is “each number n appears n times”. You can make this sequence in a very unexpected way with squareroots.

If you round sqrt(2x) to the nearest whole numbers, you also get the same sequence!

[oeistournament]

Announcement: OEIS Tournament

OEIS Tournament Submission Form

This is @pc36thorn. Recently, I had the idea to do a poll bracket tournament on Tumblr with sequences from the OEIS (On-Line Encyclopedia of Integer Sequences). To determine the competitors, I will be accepting submissions. I have not yet decided how many competitors there will be, or when to cut off submissions. The rules for submissions are in the Google Form linked above. Seeding will be determined by how many submission a sequence gets, so don't be afraid to submit all your favorites even if they might have already been submitted.

[elation0]

A112798: Table where n-th row is factorization of n, with each prime p_i replaced by i. vs A122111: Self-inverse permutation of the positive integers induced by partition enumeration in A112798 and partition conjugation.

[curiosamathematica]

The Math of Adele’s Album Releases: Can a Hidden Pattern Help Predict When She’ll Release Next?

Adele knows how to keep us waiting. Rumour Has It, Adele’s fourth studio album will release on November 19. After her debut album "19", fans waited three years for her second album, and four years for her third. But for her "30" album release, fans have waited more than six years. So what can math tell us about this pattern of Adele’s album releases? And can we use this hidden pattern to predict when she’ll release her next grand emotional return?

A great introduction to the Online Encyclopedia of Integer Sequences by means of Adele’s studio albums.

[squareallworthy]

So I noticed that today, 12/22/21 is a palindrome date, and also if written as on a calculator an upside-down palindrome date, and also 122221 = 11 * 11111, so this is the last date that is in integer sequence A308365 (numbers which are products of repunits) for a long time. And I thought that was neat.