OFFSET
0,4
EXAMPLE
The a(0) = 0 through a(4) = 10 pairs:
. . (2)(11) (3)(21) (4)(22)
(3)(111) (4)(31)
(21)(111) (22)(31)
(4)(211)
(22)(211)
(31)(211)
(4)(1111)
(22)(1111)
(31)(1111)
(211)(1111)
MAPLE
a:= n-> binomial(combinat[numbpart](n), 2):
seq(a(n), n=0..36); # Alois P. Heinz, Feb 07 2024
MATHEMATICA
Table[Binomial[PartitionsP[n], 2], {n, 0, 6}]
PROG
(PARI) a(n) = binomial(numbpart(n), 2); \\ Michel Marcus, Jul 05 2022
CROSSREFS
KEYWORD
nonn
AUTHOR
Gus Wiseman, Jul 04 2022
STATUS
approved