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oeis.org/A005245, 1, 2, 3, 4, 5, 5, 6, 6, 6, 7, 8, 7, 8, 8, 8,... minimum number of 1s needed to write n using +, * ( and ) Writte as ||n||. Open problem: For all k>0, is ||2^k || = 2k ? An open elementary number theory problem where unlike many others, we're really uncertain about the answer.

oeis.org/A022493 The Fishburn numbers count the number of unlabeled interval orders on n points. Fishburn raised the enumeration in his 1985 monograph, but the problem remained open until 2009, when Bousquét-Melou et al defined a class of sequences and found a bijection. They then used the

sequence description and connections to pattern-avoiding permutations to find a generating function. *bam* that generating function had appeared in the literature before, but without anyone connecting the structures there to interval orders. Oh, I’d be remiss if I didn’t note that the interval

orders permitting a representation in which every interval has unit length (often called semiorders) had been enumerated long before, and they are one of the myriad collections counted by the Catalan numbers!

A000521: "Coefficients of modular function j as power series in q = e^(2 Pi i t). Another name is the elliptic modular invariant J(tau)." 1, 744, 196884, 21493760, … I like this one because I discovered a Mathematica bug because of it! (And fixed the offending Mma code in OEIS) oeis.org/A000521

oeis.org/A000105 Number of free polyominoes with n cells. I like polyominoes (and other polyforms) because they each have their individual personalities, and there are endless puzzles and variations to be discovered.

bsky.app/profile/oeis...

oeis.org/A366192 Formerly named "Peter's List: Fractions nobody needs (because they can be reduced to a simpler form)." I like the idea that fractions might be sad because nobody needs them.

The beginning: list of finite groups of order n oeis.org/A000001

Question -- is a 'group' any formal bsky configuration, or just that we'll all follow your creations?