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.

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A007279 Number of partitions of n into partition numbers.

Original entry on oeis.org

1, 1, 2, 3, 4, 6, 8, 11, 14, 18, 23, 29, 36, 44, 54, 66, 79, 95, 113, 133, 157, 184, 216, 250, 290, 335, 385, 442, 505, 576, 656, 743, 842, 951, 1070, 1204, 1351, 1514, 1691, 1887, 2102, 2336, 2595, 2875, 3184, 3519, 3883, 4282, 4713, 5181, 5690, 6241, 6839, 7482
Offset: 0

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Keywords

References

  • N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence).

Crossrefs

Programs

  • Maple
    with(combinat): gf := 1/product((1-q^numbpart(k)), k=1..20): s := series(gf, q, 200): for i from 0 to 199 do printf(`%d,`,coeff(s, q, i)) od: # James Sellers, Feb 08 2002
  • Mathematica
    CoefficientList[ Series[1/Product[1 - x^PartitionsP[i], {i, 1, 15}], {x, 0, 50}], x]
  • PARI
    seq(n)={my(t=1); while(numbpart(t+1)<=n, t++); Vec(1/prod(k=1, t, 1-x^numbpart(k) + O(x*x^n)))} \\ Andrew Howroyd, Jun 22 2018

Formula

G.f.: 1/Product_{k>=1} (1-q^A000041(k)). - Michel Marcus, Jun 20 2018

Extensions

More terms from James Sellers, Feb 08 2002
a(0)=1 prepended by Alois P. Heinz, Jul 02 2017

A280253 Expansion of Product_{k>=1} (1 + x^p(k)), where p(k) is the number of partitions of k (A000041).

Original entry on oeis.org

1, 1, 1, 2, 1, 2, 2, 2, 3, 2, 3, 3, 3, 3, 3, 4, 4, 4, 5, 4, 4, 5, 5, 6, 5, 6, 6, 6, 6, 6, 7, 6, 7, 8, 7, 7, 8, 8, 9, 8, 9, 9, 9, 10, 9, 11, 9, 10, 12, 10, 11, 11, 11, 12, 11, 12, 13, 13, 14, 14, 14, 13, 13, 15, 15, 14, 15, 15, 15, 15, 15, 16, 16, 16, 17, 17, 15, 17, 19, 19, 20, 19, 20, 20, 19, 21, 20, 20, 21, 21, 22
Offset: 0

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Author

Ilya Gutkovskiy, Dec 30 2016

Keywords

Comments

Number of partitions of n into distinct partition numbers.

Examples

			a(8) = 3 because we have [7, 1], [5, 3] and [5, 2, 1].
		

Crossrefs

Programs

  • Mathematica
    nmax = 90; CoefficientList[Series[Product[(1 + x^PartitionsP[k]), {k, 1, nmax}], {x, 0, nmax}], x]

Formula

G.f.: Product_{k>=1} (1 + x^p(k)).
Showing 1-2 of 2 results.