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A348703
a(n) = Sum_{x_1+x_2+ ... +x_n=n, 0 <= x_1, x_2, ... , x_n <= n} ((n-1)*n)!/((n-x_1)! * (n-x_2)! * ... * (n-x_n)!).
3
1, 1, 4, 510, 6745200, 19038823123320, 19549762329157865925120, 11131011767163918530071193512089600, 4977434038774545402380656971924547417738384800000
OFFSET
0,3
PROG
(Ruby)
def f(n)
return 1 if n < 2
(1..n).inject(:*)
end
def A(k, n)
sum = 0
m = f((k - 1) * n)
(0..n).to_a.repeated_permutation(k){|i|
if (0..k - 1).inject(0){|s, j| s + i[j]} == n
sum += m / (0..k - 1).inject(1){|s, j| s * f(n - i[j])}
end
}
sum
end
def A348703(n)
(0..n).map{|i| A(i, i)}
end
p A348703(7)
CROSSREFS
KEYWORD
nonn
AUTHOR
Seiichi Manyama, Oct 30 2021
STATUS
approved