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 A081298 #7 Sep 08 2022 08:45:09
%S A081298 1,1,7,25,461,2821,84883,734161,30684601,342800821,18348174791,
%T A081298 251203133545,16394732478853,265727053328101,20464206411678331,
%U A081298 383172119935376161,34011762638354230001,722380674949394645269
%N A081298 Main diagonal of the square array A081297.
%H A081298 Vincenzo Librandi, <a href="/A081298/b081298.txt">Table of n, a(n) for n = 0..200</a>
%F A081298 a(n) = ((n+1)^(n+1)-(-n)^(n+1))/(2n+1).
%t A081298 Table[((n + 1)^(n + 1) - (-n)^(n + 1)) / (2 n + 1),{n, 0, 20}] (* _Vincenzo Librandi_, Aug 07 2013 *)
%o A081298 (Magma) [((n+1)^(n+1)-(-n)^(n+1))/(2*n+1): n in [0..20]]; // _Vincenzo Librandi_, Aug 07 2013
%Y A081298 Cf. A081299, A081300, A081301, A081302.
%K A081298 easy,nonn
%O A081298 0,3
%A A081298 _Paul Barry_, Mar 17 2003