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 A376057 #23 Jul 09 2025 05:05:47
%S A376057 1,2,14,994,6917246,430634636937890,2039908095836912108987531110990,
%T A376057 54095925512992695768212345567905438957243461489279855615252290
%N A376057 a(n) is the denominator of the sum S(n) defined in A376056.
%H A376057 Alois P. Heinz, <a href="/A376057/b376057.txt">Table of n, a(n) for n = 0..11</a>
%F A376057 a(n+1) = (2*n+1)*a(n)^2 + a(n), with a(0) = 1.
%e A376057 The first few values of S(n) are 0/1, 1/2, 13/14, 993/994, 6917245/6917246, 430634636937889/430634636937890, ...
%p A376057 a:= proc(n) a(n):= `if`(n=0, 1, ((2*n-1)*a(n-1)+1)*a(n-1)) end:
%p A376057 seq(a(n), n=0..7); # _Alois P. Heinz_, Oct 18 2024
%t A376057 RecurrenceTable[{a[n+1] == (2*n+1)*a[n]^2 + a[n], a[0] == 1}, a, {n, 0, 7}] (* _Amiram Eldar_, Sep 15 2024 *)
%Y A376057 Cf. A374663, A375516, A375531, A375532, A375781, A375522, A376048-A376056.
%K A376057 nonn,base,frac
%O A376057 0,2
%A A376057 _N. J. A. Sloane_, Sep 14 2024
%E A376057 a(0)=1 prepended by _Alois P. Heinz_, Oct 18 2024