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A368792
a(n) = (2*n-1)!! * Sum_{k=0..n} k/(2*k-1)!!.
1
0, 1, 5, 28, 200, 1805, 19861, 258200, 3873008, 65841145, 1250981765, 26270617076, 604224192760, 15105604819013, 407851330113365, 11827688573287600, 366658345771915616, 12099725410473215345, 423490389366562537093, 15669144406562813872460
OFFSET
0,3
FORMULA
a(0) = 0; a(n) = (2*n-1)*a(n-1) + n.
PROG
(PARI) a001147(n) = prod(k=1, n, 2*k-1);
a(n) = a001147(n)*sum(k=0, n, k/a001147(k));
CROSSREFS
KEYWORD
nonn,easy
AUTHOR
Seiichi Manyama, Jan 05 2024
STATUS
approved