cp's OEIS Frontend

This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.

A281616 Expansion of Sum_{p prime, i>=1} x^(p^i)/(1 - x^(p^i)) / Product_{p prime, j>=1} (1 - x^(p^j)).

Original entry on oeis.org

0, 1, 1, 3, 3, 7, 8, 15, 18, 28, 36, 53, 66, 91, 117, 156, 195, 254, 318, 407, 503, 630, 777, 965, 1176, 1439, 1750, 2124, 2559, 3078, 3692, 4417, 5257, 6246, 7405, 8753, 10314, 12127, 14233, 16668, 19464, 22687, 26406, 30662, 35539, 41109, 47495, 54767, 63044, 72454, 83167, 95305, 109054, 124607, 142209, 162076, 184464
Offset: 1

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Author

Ilya Gutkovskiy, Jan 25 2017

Keywords

Comments

Total number of parts in all partitions of n into prime power parts (1 excluded).
Convolution of A001222 and A023894.

Examples

			a(9) = 18 because we have [9], [7, 2], [5, 4], [5, 2, 2], [4, 3, 2], [3, 3, 3], [3, 2, 2, 2] and 1 + 2 + 2 + 3 + 3 + 3 + 4 = 18.
		

Crossrefs

Programs

  • Mathematica
    nmax = 57; Rest[CoefficientList[Series[Sum[Floor[1/PrimeNu[i]] x^i/(1 - x^i), {i, 2, nmax}]/Product[1 - Floor[1/PrimeNu[j]] x^j, {j, 2, nmax}], {x, 0, nmax}], x]]

Formula

G.f.: Sum_{p prime, i>=1} x^(p^i)/(1 - x^(p^i)) / Product_{p prime, j>=1} (1 - x^(p^j)).