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A091605
Column 2 of triangle A091602.
2
1, 0, 2, 2, 3, 4, 7, 8, 12, 15, 21, 26, 35, 43, 57, 70, 89, 109, 138, 167, 208, 251, 309, 371, 452, 539, 652, 775, 929, 1099, 1311, 1543, 1829, 2146, 2529, 2957, 3469, 4040, 4721, 5481, 6377, 7381, 8559, 9875, 11412, 13133, 15128, 17364, 19945, 22833
OFFSET
2,3
LINKS
FORMULA
a(n) = A000726(n) - A000009(n).
EXAMPLE
a(7) counts these partitions: 511, 331, 322, 3211. - Clark Kimberling, Mar 10 2014
MATHEMATICA
d[n_] := Select[IntegerPartitions[n], Max[Length /@ Split@#] == 2 &];
t = Table[d[n], {n, 12}] (* shows partitions *)
u = Table[Length[d[n]], {n, 2, 30}] (* counts partitions *)
(* Clark Kimberling, Mar 10 2014 *)
CROSSREFS
Sequence in context: A058670 A215367 A276526 * A145468 A125554 A345867
KEYWORD
nonn
AUTHOR
Christian G. Bower, Jan 23 2004
STATUS
approved