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 A127231 #27 Jan 01 2025 15:41:20 %S A127231 2,3,25,721,40321,3628801,479001601,87178291201,20922789888001, %T A127231 6402373705728001,2432902008176640001,1124000727777607680001, %U A127231 620448401733239439360001,403291461126605635584000001,304888344611713860501504000001,265252859812191058636308480000001 %N A127231 a(n) = (2n)! + 1. %t A127231 Array[(2#)!+1&,16,0] (* _James C. McMahon_, Dec 30 2024 *) %Y A127231 a(n) = 1 + A010050(n). %Y A127231 Cf. A000142, A028387, A062938, A127227, A127228, A127229, A127230. %K A127231 nonn %O A127231 0,1 %A A127231 _Artur Jasinski_, Jan 09 2007 %E A127231 Entry revised by _N. J. A. Sloane_, Mar 26 2021