OFFSET
1,2
LINKS
Alois P. Heinz, Table of n, a(n) for n = 1..78
Shyam Visweswaran and Gregory F. Cooper, Counting Markov blanket structures, arXiv:1407.2483 [stat.ML], 2014
FORMULA
a(1) = 1; for n > 1, a(n) = Sum_{q=0..n-1} Sum_{r=0..n-q-1} ((n-1)!/(q!*r!*s!))*2^(q*s)*2^(r*s) * A003024(s); n-1=q+r+s.
MATHEMATICA
(* b = A003024 *) b[0] = b[1] = 1; b[n_] := b[n] = Sum[-(-1)^k Binomial[n, k] 2^(k(n-k)) b[n-k], {k, 1, n}];
a[n_] := Sum[Sum[s = n-q-r-1; ((n-1)!/(q! r! s!)) 2^(q s) 2^(r s) b[s], {r, 0, n-q-1}], {q, 0, n 1}];
Array[a, 15] (* Jean-François Alcover, Nov 28 2018 *)
CROSSREFS
KEYWORD
nonn
AUTHOR
Shyam Visweswaran, Jul 10 2014
STATUS
approved