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 A001418 M4587 N1956 #54 Mar 21 2025 15:45:20 %S A001418 1,8,1368,300608,186086600,123912532224,129950723279272 %N A001418 Number of ways of folding an n X n sheet of stamps. %D A001418 N. J. A. Sloane, A Handbook of Integer Sequences, Academic Press, 1973 (includes this sequence). %D A001418 N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence). %H A001418 W. F. Lunnon, <a href="https://doi.org/10.1093/comjnl/14.1.75">Multi-dimensional map-folding</a>, Computer Journal 14 1971 75-80. %H A001418 Eric Weisstein's World of Mathematics, <a href="https://mathworld.wolfram.com/MapFolding.html">Map Folding</a>. %H A001418 <a href="/index/Fo#fold">Index entries for sequences obtained by enumerating foldings</a>. %e A001418 For n = 2 the a(2) = 8 foldings of a sheet labeled 1234 in reading order are 1243, 1342, 2134, 2431, 3124, 3421, 4213, 4312. %Y A001418 Cf. A000136, A000560, A001417, A195646. %K A001418 nonn,hard,more %O A001418 1,2 %A A001418 _N. J. A. Sloane_ %E A001418 a(6)-a(7) from _Sean A. Irvine_, Jan 11 2018 %E A001418 Offset corrected by _Anders Kaseorg_, Nov 29 2024