A087539 First differences of A011849.

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

Links

Table of n, a(n) for n=1..56.

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

Adjacent sequences: A087536 A087537 A087538 * A087540 A087541 A087542

Keyword

nonn,easy

Author

Ralf Stephan, Oct 24 2003

Status

approved