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A087539
First differences of A011849.
0
0, 0, 1, 2, 3, 5, 7, 10, 12, 15, 18, 22, 26, 30, 35, 40, 46, 51, 57, 63, 70, 77, 84, 92, 100, 109, 117, 126, 135, 145, 155, 165, 176, 187, 199, 210, 222, 234, 247, 260, 273, 287, 301, 316, 330, 345, 360, 376, 392, 408, 425, 442, 460, 477, 495, 513
OFFSET
1,4
FORMULA
[ C(n+1, 3)/3 ] - [ C(n, 3)/3 ].
G.f.: [x^3(1-x+x^2)(1-x^2+x^3)]/[(1-x)^3(1+x^3+x^6)].
CROSSREFS
Sequence in context: A119565 A119592 A191892 * A140690 A004684 A350102
KEYWORD
nonn,easy
AUTHOR
Ralf Stephan, Oct 24 2003
STATUS
approved