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A011874 [ n(n-1)/21 ]. 1
0, 0, 0, 0, 0, 0, 1, 2, 2, 3, 4, 5, 6, 7, 8, 10, 11, 12, 14, 16, 18, 20, 22, 24, 26, 28, 30, 33, 36, 38, 41, 44, 47, 50, 53, 56, 60, 63, 66, 70, 74, 78, 82, 86, 90, 94, 98, 102, 107, 112, 116, 121, 126, 131, 136, 141 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,8

LINKS

Table of n, a(n) for n=0..55.

FORMULA

G.f.: x^6(1-x^2+x^3+x^9-x^10+x^12)/((1-x)^2*(1-x^21)). [From R. J. Mathar, Sep 09 2008]

CROSSREFS

Sequence in context: A118868 A017885 A274165 * A000115 A033552 A062420

Adjacent sequences:  A011871 A011872 A011873 * A011875 A011876 A011877

KEYWORD

nonn

AUTHOR

N. J. A. Sloane.

STATUS

approved

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Last modified November 18 12:21 EST 2017. Contains 294891 sequences.