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 A020955 #28 Sep 02 2018 03:31:40
%S A020955 1,1,2,81,4194304,1490116119384765625,
%T A020955 226267027688376192080197927193400943822503936,
%U A020955 258086210989349276047917817413172383631691140276099547911280598425927853437317437263620645695945672001
%N A020955 a(n) = n^(2^n - n - 1).
%C A020955 Number of finite models of natural number on the free class with n members.
%H A020955 Yasutoshi Kohmoto, <a href="http://boat.zero.ad.jp/~zbi74583/another02.htm">The Other Side of Mathematics</a> [broken link?]
%H A020955 Yasutoshi Kohmoto, <a href="http://web.archive.org/web/20120409075427/http://boat.zero.ad.jp/~zbi74583/another02.htm">The Other Side of Mathematics</a> [via Internet Archive Wayback-machine]
%F A020955 a(n) = A097547(n)/A007778(n), n > 0. - _R. J. Mathar_, Jan 12 2017
%e A020955 For n=2, a(2)=2, universe class={0,1}.
%e A020955 1 : { }ma 0, {0}ma 1, {0,1}ma 1, {1}ma 0,
%e A020955 2 : { }ma 0, {0}ma 1, {0,1}ma 1, {1}ma 1.
%Y A020955 Cf. A097547.
%K A020955 nonn
%O A020955 0,3
%A A020955 _Yasutoshi Kohmoto_
%E A020955 a(0)=1 and a(7) corrected by _Vincenzo Librandi_, Apr 25 2011