A025781 - OEIS

A025781

Expansion of 1/((1-x)(1-x^5)(1-x^12)).

1, 1, 1, 1, 1, 2, 2, 2, 2, 2, 3, 3, 4, 4, 4, 5, 5, 6, 6, 6, 7, 7, 8, 8, 9, 10, 10, 11, 11, 12, 13, 13, 14, 14, 15, 16, 17, 18, 18, 19, 20, 21, 22, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 40, 41, 42

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OFFSET

0,6

COMMENTS

Number of partitions of n into parts 1, 5, and 12. [Joerg Arndt, Mar 18 2013]

Up to and including a(21) this is the same as the expansion of product_{k>=1} 1/(1-x^(k*(3*k-1)/2))), which appears as a convolution factor in A095699. - R. J. Mathar, Mar 18 2013

LINKS

Table of n, a(n) for n=0..62.

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

FORMULA

a(0)=1, a(1)=1, a(2)=1, a(3)=1, a(4)=1, a(5)=2, a(6)=2, a(7)=2, a(8)=2, a(9)=2, a(10)=3, a(11)=3, a(12)=4, a(13)=4, a(14)=4, a(15)=5, a(16)=5, a(17)=6, a(n)=a(n-1)+a(n-5)-a(n-6)+a(n-12)-a(n-13)-a(n-17)+a(n-18). - Harvey P. Dale, May 11 2014

MATHEMATICA

CoefficientList[Series[1/((1-x)(1-x^5)(1-x^12)), {x, 0, 70}], x] (* or *) LinearRecurrence[{1, 0, 0, 0, 1, -1, 0, 0, 0, 0, 0, 1, -1, 0, 0, 0, -1, 1}, {1, 1, 1, 1, 1, 2, 2, 2, 2, 2, 3, 3, 4, 4, 4, 5, 5, 6}, 70] (* Harvey P. Dale, May 11 2014 *)

CROSSREFS

Sequence in context: A286707 A025788 A071806 * A218379 A242763 A018119

Adjacent sequences: A025778 A025779 A025780 * A025782 A025783 A025784

KEYWORD

nonn

AUTHOR

N. J. A. Sloane.

STATUS

approved