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 A137157 #7 Jan 04 2023 18:17:11
%S A137157 1,2,5,24,239,4920,206727,17568408,3003763243,1030272816360,
%T A137157 707851744149198,973425618916674288,2678332881795756783639,
%U A137157 14741522294008025924154864,162290544340043699103996962253,3573515596966915773419766367302288,157376160486791180710467411977740266927
%N A137157 G.f.: 1 = Sum_{n>=0} a(n)*x^n/(1+x)^(2*2^n).
%C A137157 Equals unsigned column 1 of triangle A137156.
%o A137157 (PARI) {a(n)=polcoeff(1-sum(k=0, n-1, a(k)*x^k/(1+x+x*O(x^n))^(2^(k+1)) ), n)}
%Y A137157 Cf. A137156; A001192, A137158, A137159, A137160.
%K A137157 nonn
%O A137157 0,2
%A A137157 _Paul D. Hanna_, Jan 24 2008
%E A137157 a(15)-a(16) from _Alois P. Heinz_, Jan 04 2023