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 A256401 #13 Mar 30 2015 09:42:05
%S A256401 1,-1,0,1,-1,1,1,-5,-8,43,-74,-559,697,-13232,-30727,450991,-5519014,
%T A256401 8250311,59081053,-2113948301,19352683736,-113555728681,-4421555920,
%U A256401 10403170713454,4947541575776,-1037548987977353,4668788227294924,20521746955820009
%N A256401 Numerators of coefficients of expansion of exp(-Sum_{k=0..oo} x^(2^k)/2^k ) in powers of x.
%H A256401 Hiroaki Yamanouchi, <a href="/A256401/b256401.txt">Table of n, a(n) for n = 0..100</a>
%H A256401 Koda, Tatsuhiko; Sato, Masaki; Takegahara, Yugen; <a href="http://dx.doi.org/10.1142/S0219498815500528">2-adic properties for the numbers of involutions in the alternating groups</a>, J. Algebra Appl. 14 (2015), no. 4, 1550052 (21 pages). See Lemma 2.1.
%Y A256401 For denominators see A256402. Cf. A256400.
%K A256401 sign,frac
%O A256401 0,8
%A A256401 _N. J. A. Sloane_, Mar 29 2015
%E A256401 a(18)-a(27) from _Hiroaki Yamanouchi_, Mar 30 2015