A035636 Number of partitions of n into parts 5k+3 and 5k+4 with at least one part of each type.
0, 0, 0, 0, 0, 0, 1, 0, 0, 1, 1, 2, 1, 1, 3, 3, 4, 3, 4, 7, 7, 8, 8, 10, 14, 14, 16, 18, 20, 27, 28, 30, 35, 40, 48, 52, 55, 64, 73, 85, 90, 98, 114, 128, 143, 155, 168, 195, 214, 237, 259, 283, 319, 353, 385, 422, 460, 516, 564, 618, 672, 734, 816, 892, 964, 1057
Offset: 1
Keywords
Links
- Robert Price, Table of n, a(n) for n = 1..1000
Programs
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Mathematica
nmax = 66; s1 = Range[0, nmax/5]*5 + 3; s2 = Range[0, nmax/5]*5 + 4; Table[Count[IntegerPartitions[n, All, s1~Join~s2], x_ /; ContainsAny[x, s1 ] && ContainsAny[x, s2 ]], {n, 1, nmax}] (* Robert Price, Aug 07 2020 *) nmax = 66; l = Rest@CoefficientList[Series[(-1 + 1/Product[(1 - x^(5 k + 3)), {k, 0, nmax}])*(-1 + 1/Product[(1 - x^(5 k + 4)), {k, 0, nmax}]), {x, 0, nmax}], x] (* Robert Price, Aug 16 2020 *)
Formula
G.f.: (-1 + 1/Product_{k>=0} (1 - x^(5 k + 3)))*(-1 + 1/Product_{k>=0} (1 - x^(5 k + 4))). - Robert Price, Aug 16 2020