A035961 Number of partitions of n into parts not of the form 15k, 15k+7 or 15k-7. Also number of partitions with at most 6 parts of size 1 and differences between parts at distance 6 are greater than 1.

1, 1, 2, 3, 5, 7, 11, 14, 20, 27, 37, 48, 65, 83, 109, 139, 179, 225, 287, 357, 449, 556, 691, 848, 1047, 1276, 1561, 1893, 2299, 2772, 3348, 4015, 4820, 5756, 6874, 8171, 9716, 11501, 13614, 16058, 18932, 22249, 26138, 30613, 35838, 41848, 48831

Offset

0,3

Comments

Case k=7,i=7 of Gordon Theorem.

References

G. E. Andrews, The Theory of Partitions, Addison-Wesley, 1976, p. 109.

Links

Seiichi Manyama, Table of n, a(n) for n = 0..1000

Formula

a(n) ~ exp(2*Pi*sqrt(2*n/15)) * 2^(1/4) * cos(Pi/30) / (15^(3/4) * n^(3/4)). - Vaclav Kotesovec, May 10 2018

Mathematica

With[ {n=30}, Series[ 1/Product[ (1 - Switch[ Mod[ k, 15 ], 0, 0, 7, 0, 8, 0, _, x^k ]), {k, 1, n} ], {x, 0, n} ] ]
nmax = 60; CoefficientList[Series[Product[(1 - x^(15*k))*(1 - x^(15*k+ 7-15))*(1 - x^(15*k- 7))/(1 - x^k), {k, 1, nmax}], {x, 0, nmax}], x] (* Vaclav Kotesovec, May 10 2018 *)

Crossrefs

Sequence in context: A363068 A238864 A070289 * A051056 A055803 A023027

Adjacent sequences: A035958 A035959 A035960 * A035962 A035963 A035964

Keyword

nonn,easy

Author

Olivier Gérard

Extensions

a(0)=1 prepended by Seiichi Manyama, May 08 2018

Status

approved