|
%I #5 Oct 08 2018 18:15:35
%S 1,1,3,16,125,1291,16177,241207,4153193,81082225,1770989921,
%T 42763506919,1131353484637,32541516492811,1011058416700529,
%U 33745374949198231,1204107124715441873,45741398365345761073,1843069565594762478145,78511973999963036415967,3525468554804288803649381
%N a(n) = n! * [x^n] exp(exp(x)*(x + (n/2 - 1)*x^2)).
%C For n > 2, a(n) is the n-th term of the exponential transform of n-gonal numbers.
%H N. J. A. Sloane, <a href="/transforms.txt">Transforms</a>
%H <a href="/index/Pol#polygonal_numbers">Index to sequences related to polygonal numbers</a>
%t Table[n! SeriesCoefficient[Exp[Exp[x] (x + (n/2 - 1) x^2)], {x, 0, n}], {n, 0, 20}]
%Y Cf. A000248, A033462, A279361, A279644, A318118, A318124, A320255.
%K nonn
%O 0,3
%A _Ilya Gutkovskiy_, Oct 08 2018
|
