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.

Showing 1-2 of 2 results.

A298604 Number of partitions of n into distinct odd prime parts (including 1).

Original entry on oeis.org

1, 1, 0, 1, 1, 1, 1, 1, 2, 1, 1, 2, 2, 2, 2, 2, 3, 3, 3, 4, 4, 4, 4, 5, 6, 5, 5, 6, 6, 7, 7, 8, 9, 8, 9, 10, 11, 12, 11, 12, 14, 14, 15, 16, 17, 17, 17, 20, 22, 21, 22, 24, 25, 27, 28, 30, 31, 31, 33, 36, 39, 40, 40, 42, 46, 47, 49, 53, 54, 55, 58, 63, 67, 68, 70, 73, 77, 81, 84
Offset: 0

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Author

Ilya Gutkovskiy, Jan 22 2018

Keywords

Examples

			a(16) = 3 because we have [13, 3], [11, 5] and [7, 5, 3, 1].
		

Crossrefs

Programs

  • Mathematica
    nmax = 78; CoefficientList[Series[(1 + x) Product[(1 + x^Prime[k]), {k, 2, nmax}], {x, 0, nmax}], x]

Formula

G.f.: (1 + x)*Product_{k>=2} (1 + x^prime(k)).

A309676 Number of compositions (ordered partitions) of n into odd primes (including 1).

Original entry on oeis.org

1, 1, 1, 2, 3, 5, 8, 13, 21, 33, 53, 86, 138, 222, 357, 573, 921, 1481, 2381, 3828, 6153, 9890, 15898, 25556, 41082, 66039, 106156, 170644, 274307, 440945, 708815, 1139412, 1831589, 2944253, 4732847, 7607989, 12229743, 19659153, 31601828, 50799517, 81659549
Offset: 0

Views

Author

Ilya Gutkovskiy, Aug 12 2019

Keywords

Crossrefs

Programs

  • Maple
    a:= proc(n) option remember; `if`(n=0, 1, a(n-1)+
          add(`if`(isprime(j), a(n-j), 0), j=3..n))
        end:
    seq(a(n), n=0..42);  # Alois P. Heinz, Aug 12 2019
  • Mathematica
    nmax = 42; CoefficientList[Series[1/(1 - x - Sum[x^Prime[k], {k, 2, nmax}]), {x, 0, nmax}], x]
    a[0] = 1; a[n_] := a[n] = Sum[Boole[PrimeOmega[k] < 2 && OddQ[k]] a[n - k], {k, 1, n}]; Table[a[n], {n, 0, 42}]

Formula

G.f.: 1/(1 - x - Sum_{k>=2} x^prime(k)).
Showing 1-2 of 2 results.