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 A385419 #11 Jun 28 2025 10:04:56
%S A385419 1,1,3,11,57,489,5067,50595,573297,9323985,168823443,2679252795,
%T A385419 45149256105,1121782132665,29930127386715,629179051311315,
%U A385419 13329925622622945,472248682257228705,17395967794618282275,434384524558247177835,10095605146704332967705
%N A385419 Expansion of e.g.f. 1/(1 - arcsinh(2*x))^(1/2).
%C A385419 a(32) = -243211075187578815197768727974208613120575.
%F A385419 E.g.f.: 1/(1 - log(2*x + sqrt(4*x^2 + 1)))^(1/2).
%F A385419 a(n) = Sum_{k=0..n} A001147(k) * (2*i)^(n-k) * A385343(n,k), where i is the imaginary unit.
%o A385419 (PARI) my(N=30, x='x+O('x^N)); Vec(serlaplace(1/(1-asinh(2*x))^(1/2)))
%Y A385419 Cf. A296675, A385420.
%Y A385419 Cf. A001147, A385371, A385343.
%K A385419 sign
%O A385419 0,3
%A A385419 _Seiichi Manyama_, Jun 28 2025