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.

A054685 Number of partitions of n into distinct prime powers (1 not considered a power).

Original entry on oeis.org

1, 0, 1, 1, 1, 2, 1, 3, 2, 4, 3, 5, 5, 6, 7, 7, 10, 9, 12, 12, 15, 15, 18, 19, 22, 24, 26, 30, 32, 36, 39, 43, 48, 51, 57, 61, 68, 73, 79, 87, 93, 103, 108, 121, 127, 140, 148, 162, 173, 187, 200, 215, 232, 247, 266, 283, 306, 324, 348, 371, 397, 423, 450, 480, 512, 543, 579, 614
Offset: 0

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Author

David W. Wilson, Apr 19 2000

Keywords

Crossrefs

Cf. A051613.
Cf. A106244.
Cf. A000961.

Programs

  • Haskell
    import Data.MemoCombinators (memo2, integral)
    a054685 n = a054685_list !! n
    a054685_list = map (p' 2) [0..] where
       p' = memo2 integral integral p
       p _ 0 = 1
       p k m = if m < pp then 0 else p' (k + 1) (m - pp) + p' (k + 1) m
               where pp = a000961 k
    -- Reinhard Zumkeller, Nov 23 2015
  • Mathematica
    CoefficientList[Series[Product[Product[1 +x^(Prime[n]^k), {k, 1, 9}], {n, 1, 25}], {x, 0, 100}], x] (* G. C. Greubel, May 09 2019 *)

Formula

G.f.: Product_{p prime} Product_{k >= 1} (1 + x^(p^k)).