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 A006572 M3817 #21 Jul 08 2025 16:49:43
%S A006572 0,0,1,5,11,-203,-17207,-3607,1408301,8181503,-3299598169,
%T A006572 -14983154641,-449428440959,2480887997789,19076621521399973,
%U A006572 -31806561859970819,-3485566370059659659,-2180443004193000007,54188073629843061671671
%N A006572 Numerators of an asymptotic expansion for the number of forests on n nodes (A001858).
%C A006572 Takacs Table 2 gives incorrect A006572(10)/A006573(10) = -137483257/61440 and A006572(11)/A006573(11) = -24971924401/983040. - _Sean A. Irvine_, May 11 2017
%D A006572 N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence).
%D A006572 L. Takacs, On the number of distinct forests, SIAM J. Discrete Math., 3 (1990), 574-581.
%F A006572 a(n) = numerator(Sum_{i=1..floor(n/2)} (-1)^(i-1) * |A111999(n, 2*i-1)| / (2^(n-i) * (n-i)!)). - _Sean A. Irvine_, May 11 2017
%Y A006572 Cf. A006573, A001858, A111999.
%K A006572 sign,frac
%O A006572 0,4
%A A006572 _N. J. A. Sloane_
%E A006572 a(10) and a(11) corrected and more terms from _Sean A. Irvine_, May 11 2017