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 A127230 #9 Mar 27 2021 15:22:31
%S A127230 1,23,719,40319,3628799,479001599,87178291199,20922789887999,
%T A127230 6402373705727999,2432902008176639999,1124000727777607679999,
%U A127230 620448401733239439359999,403291461126605635583999999,304888344611713860501503999999,265252859812191058636308479999999
%N A127230 a(n) = (2n)! - 1.
%F A127230 a(n) = -1 + A010050(n).
%t A127230 Table[(2n)! - 1, {n, 1, 30}]
%Y A127230 Cf. A010050, A028387, A062938, A127227, A127228, A127229, A127231.
%K A127230 nonn
%O A127230 1,2
%A A127230 _Artur Jasinski_, Jan 09 2007
%E A127230 Entry revised by _Alois P. Heinz_, Mar 27 2021