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 A279020 #5 Dec 03 2016 12:06:34
%S A279020 0,1,3,85,21652,67690148,3158065145088,2600806474859606784,
%T A279020 43634288683151793919033344,16904817514490272003065681518985216,
%U A279020 169048175123324778807714958980684133171200000,48231417258392463006590622244366007983063473271603200000
%N A279020 a(n) = unreduced numerator in Sum_{k=1..n} (-1)^(k-1)/k^k.
%H A279020 Daniel Suteu, <a href="/A279020/b279020.txt">Table of n, a(n) for n = 0..19</a>
%H A279020 Wikipedia, <a href="https://en.wikipedia.org/wiki/Sophomore's_dream">Sophomore's dream</a>.
%F A279020 a(n) ~ A083648 * A002109(n).
%F A279020 a(0) = 0, a(n) = n^n * a(n-1) + (-1)^(n-1) * A002109(n-1).
%o A279020 (PARI) sum(k=1, n, (-1)^(k-1)/k^k) * prod(k=1, n, k^k)
%Y A279020 Cf. A083648.
%K A279020 nonn,easy
%O A279020 0,3
%A A279020 _Daniel Suteu_, Dec 03 2016