OFFSET
0,4
LINKS
FORMULA
EXAMPLE
a(5) = 4 because we have [4, 1], [3, 2], [2, 3] and [1, 4].
MAPLE
b:= proc(n, i, p) option remember; `if`(i*(i+1)/2<n, 0, `if`(n=0,
irem(p+1, 2)*p!, add(b(n-i*j, i-1, p+j), j=0..min(1, n/i))))
end:
a:= n-> b(n$2, 0):
seq(a(n), n=0..55); # Alois P. Heinz, Feb 09 2020
MATHEMATICA
nmax = 45; CoefficientList[Series[Sum[(2 k)! x^(k (2 k + 1))/Product[1 - x^j, {j, 1, 2 k}], {k, 0, nmax}], {x, 0, nmax}], x]
CROSSREFS
KEYWORD
nonn
AUTHOR
Ilya Gutkovskiy, Feb 09 2020
STATUS
approved