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 A343846 #17 May 06 2021 12:20:24
%S A343846 0,2,6,40,350,4032,56364,933504,17824950,385848320,9334057876,
%T A343846 249576198144,7308698191340,232643283353600,7997684730384600,
%U A343846 295306112919306240,11655857682806336550,489743069731226910720,21824608434847162167300,1028154317960939805081600
%N A343846 a(n) = binomial(2*n, n)*2^n*|Euler(n, 1/2) - Euler(n, 0)|.
%F A343846 a(n) = binomial(2*n, n) * |Euler(n) - 2^n*Euler(n, 0)|.
%F A343846 a(n) = A109449(2*n, n) for n >= 1.
%F A343846 a(n) = (-1)^binomial(n, 2) * binomial(2*n, n) * A163747(n).
%F A343846 a(n) ~ 2^(3*n + 5/2) * n^n / (Pi^(n+1) * exp(n)). - _Vaclav Kotesovec_, May 06 2021
%p A343846 a := n -> binomial(2*n, n)*abs(euler(n) - 2^n*euler(n, 0)):
%p A343846 seq(a(n), n=0..19);
%t A343846 Table[Binomial[2*n, n]*Abs[EulerE[n] - 2^n*EulerE[n, 0]], {n, 0, 20}] (* _Vaclav Kotesovec_, May 06 2021 *)
%Y A343846 Cf. A109449, A163747.
%K A343846 nonn
%O A343846 0,2
%A A343846 _Peter Luschny_, May 06 2021