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 A367530 #28 Jul 08 2024 10:38:10 %S A367530 1,4,32,2081,671104,954448620,5744387279872,144115188176529540, %T A367530 14925010118699132241920,6338253001141163895983922592, %U A367530 10985355337065420437221545952731136,77433143050453552574825990883161180320096,2213872302702432822841084717014014514981767643136 %N A367530 The number of ways of tiling the n X n torus up to matrix transposition by a tile that is asymmetric with respect to matrix transposition. %C A367530 The n X n torus is an n X n grid where two grids are considered the same if one can reach the other by cyclic shifting of rows and columns. %H A367530 Peter Kagey, <a href="/A367530/a367530_2.pdf">Illustration of a(3) = 32</a> %H A367530 Peter Kagey and William Keehn, <a href="https://arxiv.org/abs/2311.13072">Counting tilings of the n X m grid, cylinder, and torus</a>, arXiv: 2311.13072 [math.CO], 2023. See also <a href="https://cs.uwaterloo.ca/journals/JIS/VOL27/Kagey/kagey6.html">J. Int. Seq.</a>, (2024) Vol. 27, Art. No. 24.6.1, pp. A-21, A-25. %t A367530 A367530[n_] := 1/(2n^2) (DivisorSum[n, Function[d, DivisorSum[n, Function[c, EulerPhi[c] EulerPhi[d] 2^(n^2/LCM[c, d])]]]] + n*DivisorSum[n, Function[d, EulerPhi[d]*Which[OddQ[d], 0, EvenQ[d], 2^(n^2/(2 d))]]]) %Y A367530 Cf. A103488, A255015. %K A367530 nonn %O A367530 1,2 %A A367530 _Peter Kagey_, Dec 13 2023