proposed
approved
proposed
approved
editing
proposed
Cf. A053490.
1, 0, 6, 9, 120, 555, 5148, 39711, 378528, 3715011, 39838260, 452684463, 5463506304, 69553644771, 930940368036, 13054086036855, 191222363275968, 2918620069099395, 46309955947643124, 762335523354333855, 12995722456718984160, 229045407317491457763
a(n) = n! * Sum_{k=0..floor(n/2)} 3^k * Stirling2(n-k,k)/(n-k)!.
(PARI) my(N=30, x='x+O('x^N)); Vec(serlaplace(exp(3*x*(exp(x)-1))))
(PARI) a(n) = n!*sum(k=0, n\2, 3^k*stirling(n-k, k, 2)/(n-k)!);
allocated for Seiichi Manyama
Expansion of e.g.f. exp( 3 * x * (exp(x) - 1) ).
1, 0, 6, 9, 120, 555, 5148, 39711, 378528, 3715011, 39838260, 452684463, 5463506304, 69553644771, 930940368036
0,3
allocated
nonn
Seiichi Manyama, May 20 2022
approved
editing
allocated for Seiichi Manyama
recycled
allocated
allocated for Andrew Howroyd
allocated
recycled