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 A275574 #10 Jun 02 2025 12:19:18
%S A275574 0,1,4,8,62,108,1200,2048,29524,50000,885780,1492992,31374258,
%T A275574 52706752,1281445312,2147483648,59293938248,99179645184,3065533128900,
%U A275574 5120000000000
%N A275574 ((-1)^n - 1 + 2*(n^floor((n + 1)/2)))/4.
%C A275574 Number of 2-r stable discrete function classes on [n] under reversal and complement to n+1.
%C A275574 f(n) == 2 (mod 4) if n == 5 mod 8, otherwise (except for n=2) f(n) == 0 (mod 4). - _Robert Israel_, Aug 09 2016
%H A275574 Robert Israel, <a href="/A275574/b275574.txt">Table of n, a(n) for n = 1..700</a>
%p A275574 f:= n -> ((-1)^n - 1 + 2*(n^floor((n + 1)/2)))/4:
%p A275574 map(f, [$1..30]); # _Robert Israel_, Aug 09 2016
%t A275574 Table[1/4 ((-1)^ n-1+2 (n)^Floor[(n+1)/2]),{n,1,20}]
%Y A275574 Cf. A275550.
%K A275574 nonn,easy
%O A275574 1,3
%A A275574 _Olivier Gérard_, Aug 02 2016