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A055610 A companion sequence to A011896. 1
0, 0, 0, 1, 2, 5, 9, 15, 24, 36, 52, 71, 95, 123, 156, 195, 240, 292, 350, 416, 489, 570, 660, 759, 868, 986, 1115, 1254, 1404, 1566, 1740, 1927, 2126, 2339, 2565, 2805, 3060, 3330, 3616, 3917, 4235, 4569, 4920, 5289, 5676, 6082, 6506, 6950, 7413, 7896 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,5

LINKS

Table of n, a(n) for n=0..49.

Index entries for linear recurrences with constant coefficients, signature (3, -3, 1, 0, 0, 0, 1, -3, 3, -1).

FORMULA

G.f.: x^3 * (1 - x + 2*x^2 - x^3 + x^4 + x^5) / ((1 - x)^3 * (1 - x^7)).

a(n) = -A011896(2 - n).

EXAMPLE

x^3 + 2*x^4 + 5*x^5 + 9*x^6 + 15*x^7 + 24*x^8 + 36*x^9 + 52*x^10 + ...

PROG

(PARI) {a(n) = ceil( n * (n-1) * (n-2) / 14)}

CROSSREFS

Cf. A011896.

Sequence in context: A014126 A019450 A098169 * A134342 A100287 A007176

Adjacent sequences:  A055607 A055608 A055609 * A055611 A055612 A055613

KEYWORD

nonn

AUTHOR

Michael Somos, Jun 02 2000

STATUS

approved

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Last modified February 20 00:28 EST 2019. Contains 320329 sequences. (Running on oeis4.)