%I M4587 N1956 #29 Dec 23 2021 23:03:17
%S 1,8,1368,300608,186086600,123912532224,129950723279272
%N Number of ways of folding an n X n sheet of stamps.
%D N. J. A. Sloane, A Handbook of Integer Sequences, Academic Press, 1973 (includes this sequence).
%D N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence).
%H W. F. Lunnon, <a href="http://dx.doi.org/10.1093/comjnl/14.1.75">Multi-dimensional map-folding</a>, Computer Journal 14 1971 75-80.
%H Eric Weisstein's World of Mathematics, <a href="http://mathworld.wolfram.com/MapFolding.html">Map Folding</a>
%H <a href="/index/Fo#fold">Index entries for sequences obtained by enumerating foldings</a>
%Y Cf. A000136, A000560, A001417, A195646.
%K nonn,hard,more
%O 0,2
%A _N. J. A. Sloane_
%E a(6)-a(7) from _Sean A. Irvine_, Jan 11 2018