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 A108398 #17 Sep 08 2022 08:45:19 %S A108398 0,1,5,42,514,7815,139971,2882404,67108868,1743392205,50000000005, %T A108398 1569214188366,53496602689542,1968688192849651,77784047778906119, %U A108398 3284204177856445320,147573952589676412936,7031542226033862495513 %N A108398 a(n) = n*(1 + n^n)/2. %H A108398 Vincenzo Librandi, <a href="/A108398/b108398.txt">Table of n, a(n) for n = 0..100</a> %F A108398 a(n) = A108396(n,n). %F A108398 E.g.f.: (exp(x) * x - LambertW(-x)/(1 + LambertW(-x))^3) / 2. - _Vaclav Kotesovec_, Jan 03 2019 %o A108398 (Magma) [n*(1+n^n)/2: n in [0..25]]; // _Vincenzo Librandi_, Apr 29 2011 %o A108398 (Haskell) %o A108398 a108398 n = n * (1 + n ^ n) `div` 2 -- _Reinhard Zumkeller_, Mar 31 2015 %Y A108398 Cf. A000312, A000217. %Y A108398 Cf. A108396, A256512. %K A108398 nonn %O A108398 0,3 %A A108398 _Reinhard Zumkeller_, Jun 02 2005