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A321948
Column k=3 of triangle A257673.
3
1, 9, 45, 174, 576, 1719, 4761, 12441, 31050, 74593, 173547, 392787, 867876, 1877322, 3984636, 8314434, 17082510, 34604523, 69194309, 136709688, 267111510, 516515227, 989147760, 1877103486, 3531796959, 6591644601, 12208734552, 22449066710, 40995144288
OFFSET
3,2
LINKS
FORMULA
G.f.: (-1 + Product_{k>=1} 1 / (1 - x^k)^k)^3. - Ilya Gutkovskiy, Jan 30 2021
MAPLE
b:= proc(n, k) option remember; `if`(n=0, 1, k*add(
b(n-j, k)*numtheory[sigma][2](j), j=1..n)/n)
end:
a:= n-> (k-> add(b(n, k-i)*(-1)^i*binomial(k, i), i=0..k))(3):
seq(a(n), n=3..35);
CROSSREFS
Column k=3 of A257673.
Sequence in context: A276280 A036826 A022574 * A050574 A124647 A111640
KEYWORD
nonn
AUTHOR
Alois P. Heinz, Nov 22 2018
STATUS
approved