This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.
%I A221844 #31 Sep 06 2021 04:29:35 %S A221844 1,1,2,11,76,1490,56977,4495010,669203525 %N A221844 Number of prime dissections of an n X n square into integer-sided squares up to symmetry. %C A221844 A dissection into squares was called prime by _J. H. Conway_ in 1964 if the GCD of the sides of the squares is 1. %H A221844 J. H. Conway, <a href="http://dx.doi.org/10.1017/S0305004100037877">Mrs. Perkins's quilt</a>, Proc. Camb. Phil. Soc., 60 (1964), 363-368. %H A221844 Ed Wynn, <a href="http://arxiv.org/abs/1308.5420">Exhaustive generation of Mrs Perkins's quilt square dissections for low orders</a>, 2013, arXiv:1308.5420 %e A221844 For n = 4 there are a(4) = 11 dissections: %e A221844 +-+-+-+-+ +---+-+-+ +-+---+-+ +-+-+-+-+ +---+---+ +---+-+-+ %e A221844 | | | | | | | | | | | | | | | | | | | | | | | | | %e A221844 +-+-+-+-+ | +-+-+ +-+ +-+ +-+-+-+-+ | | | | +-+-+ %e A221844 | | | | | | | | | | | | | | | | | | | | | | | %e A221844 +-+-+-+-+ +-+-+-+-+ +-+-+-+-+ +-+ +-+ +-+-+-+-+ +-+-+ | %e A221844 | | | | | | | | | | | | | | | | | | | | | | | | | | | | %e A221844 +-+-+-+-+ +-+-+-+-+ +-+-+-+-+ +-+-+-+-+ +-+-+-+-+ +-+-+-+-+ %e A221844 | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | %e A221844 +-+-+-+-+ +-+-+-+-+ +-+-+-+-+ +-+-+-+-+ +-+-+-+-+ +-+-+-+-+ %e A221844 ... %e A221844 +---+-+-+ +-+---+-+ +---+---+ +---+---+ +-----+-+ %e A221844 | | | | | | | | | | | | | | | | | %e A221844 | +-+-+ +-+ +-+ | | | | | | | +-+ %e A221844 | | | | | | | | | | | | | | | | | %e A221844 +-+-+-+-+ +-+---+-+ +---+-+-+ +-+-+-+-+ | +-+ %e A221844 | | | | | | | | | | | | | | | | | | | %e A221844 +-+-+ | +-+ +-+ | +-+-+ +-+ +-+ +-+-+-+-+ %e A221844 | | | | | | | | | | | | | | | | | | | | | %e A221844 +-+-+---+ +-+---+-+ +---+-+-+ +-+---+-+ +-+-+-+-+ %e A221844 ... %e A221844 For n = 5 there are a(5) = 76 dissections, each of which comprises one of A221843(5) = 10 sets of subsquares: %e A221844 . %e A221844 Subsquares Prime dissections %e A221844 4 X 4 3 X 3 2 X 2 1 X 1 (up to symmetry) %e A221844 ----- ----- ----- ----- ---------------- %e A221844 - - - 25 1 %e A221844 - - 1 21 3 %e A221844 - - 2 17 13 %e A221844 - - 3 13 20 %e A221844 - - 4 9 14 %e A221844 - 1 - 16 3 %e A221844 - 1 1 12 6 %e A221844 - 1 2 8 10 %e A221844 - 1 3 4 5 %e A221844 1 - - 9 1 %e A221844 -- %e A221844 76 %Y A221844 Cf. A221843, A221845. %K A221844 nonn,more %O A221844 1,3 %A A221844 _Geoffrey H. Morley_, Jan 26 2013 %E A221844 More terms from Wynn, 2013. - _N. J. A. Sloane_, Nov 29 2013