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 A128897 #6 Jun 08 2021 02:34:29 %S A128897 1,13,1111,233017,90909091,57154490053,52914318216943, %T A128897 67818912035696881,115047976828352449051,249660952380952380952381, %U A128897 674758650917429955329341351,2222892961417140207415135788073 %N A128897 a(n) = ((2n)^(2n-1)+1)/(2n+1). %F A128897 a(n) = ((2n)^(2n-1)+1)/(2n+1). a(n) = A083062(2n-1). %Y A128897 Cf. A083062 ((n+1)^n/(n+2) - (-1)^n/(n+2)). %K A128897 nonn %O A128897 1,2 %A A128897 _Alexander Adamchuk_, Apr 20 2007