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 1-10 of 10 results.

A218380 Number of partitions of n into distinct pentagonal parts.

Original entry on oeis.org

1, 1, 0, 0, 0, 1, 1, 0, 0, 0, 0, 0, 1, 1, 0, 0, 0, 1, 1, 0, 0, 0, 1, 1, 0, 0, 0, 1, 1, 0, 0, 0, 0, 0, 1, 2, 1, 0, 0, 1, 2, 1, 0, 0, 0, 0, 0, 1, 1, 0, 0, 1, 2, 1, 0, 0, 1, 2, 1, 0, 0, 0, 1, 2, 1, 0, 0, 0, 1, 2, 2, 1, 0, 1, 2, 2, 1, 0, 1, 1, 0, 0, 1, 1, 0, 1, 2, 2
Offset: 0

Views

Author

Antonio Roldán, Oct 27 2012

Keywords

Examples

			A(98)=3 because 98 = 12 + 35 + 51 = 1 + 5 + 92 = 1 + 5 + 22 + 70 with 1, 5, 22, 70, 92 pentagonal numbers.
		

Crossrefs

Programs

  • PARI
    { for (n=1, 100, m=polcoeff(prod(k=1, truncate(1+sqrt(24*n+1))/6, 1+x^(k*(3*k-1)/2)), n);write("B218380.txt",n, " ",m)) }

Extensions

a(0) = 1 prepended by Seiichi Manyama, Dec 09 2017

A095699 Number of partitions of n into generalized pentagonal numbers.

Original entry on oeis.org

1, 1, 2, 2, 3, 4, 5, 7, 8, 10, 12, 14, 18, 20, 25, 29, 34, 40, 45, 53, 60, 69, 80, 89, 103, 114, 131, 147, 165, 186, 207, 232, 258, 286, 319, 352, 392, 432, 477, 525, 578, 636, 699, 765, 839, 916, 1002, 1093, 1192, 1298, 1413, 1536, 1671, 1810, 1965, 2126, 2304
Offset: 0

Views

Author

Jon Perry, Jul 06 2004

Keywords

Crossrefs

Programs

  • Mathematica
    nmax = 100; CoefficientList[Series[1/Product[(1-x^(k*(3*k-1)/2)) * (1-x^(k*(3*k+1)/2)), {k, 1, nmax}], {x, 0, nmax}], x] (* Vaclav Kotesovec, Dec 10 2017 *)
  • PARI
    b(n) = (3*n^2 + 2*n + (n%2) * (2*n + 1)) / 8; \\ A001318
    N=66; x='x+O('x^N);
    Vec(1/prod(k=1,N, (1-x^b(k))) )
    \\ Joerg Arndt, Oct 13 2014

Formula

G.f.: 1/Product_{k>=1} (1-x^(k*(3*k-1)/2))*(1-x^(k*(3*k+1)/2)).

A278949 Expansion of Product_{k>=1} 1/(1 - x^(k*(2*k-1))).

Original entry on oeis.org

1, 1, 1, 1, 1, 1, 2, 2, 2, 2, 2, 2, 3, 3, 3, 4, 4, 4, 5, 5, 5, 6, 6, 6, 7, 7, 7, 8, 9, 9, 11, 11, 11, 12, 13, 13, 15, 15, 15, 16, 17, 17, 19, 20, 20, 23, 24, 24, 26, 27, 27, 30, 31, 31, 33, 34, 35, 38, 40, 40, 44, 45, 46, 49, 51, 51, 56, 57, 58, 61, 63, 64, 69, 72, 73, 78, 80, 81, 86, 89, 90, 96, 98, 99, 105, 108, 110, 116, 120, 121, 130
Offset: 0

Views

Author

Ilya Gutkovskiy, Dec 02 2016

Keywords

Comments

Number of partitions of n into nonzero hexagonal numbers (A000384).

Examples

			a(7) = 2 because we have [6, 1] and [1, 1, 1, 1, 1, 1, 1].
		

Crossrefs

Programs

  • Maple
    h:= proc(n) option remember; `if`(n<1, 0, (t->
          `if`(t*(2*t-1)>n, t-1, t))(1+h(n-1)))
        end:
    b:= proc(n, i) option remember; `if`(n=0, 1, `if`(i<1, 0,
          b(n, i-1)+(t-> b(n-t, min(i, h(n-t))))(i*(2*i-1))))
        end:
    a:= n-> b(n, h(n)):
    seq(a(n), n=0..100);  # Alois P. Heinz, Dec 28 2018
  • Mathematica
    nmax=90; CoefficientList[Series[Product[1/(1 - x^(k (2 k - 1))), {k, 1, nmax}], {x, 0, nmax}], x]

Formula

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

A280952 Expansion of Product_{k>=0} 1/(1 - x^(5*k*(k+1)/2+1)).

Original entry on oeis.org

1, 1, 1, 1, 1, 1, 2, 2, 2, 2, 2, 2, 3, 3, 3, 3, 4, 4, 5, 5, 5, 5, 6, 6, 7, 7, 7, 7, 8, 8, 9, 10, 11, 11, 12, 12, 13, 14, 15, 15, 16, 16, 17, 18, 19, 19, 20, 21, 23, 24, 25, 26, 27, 28, 30, 31, 32, 33, 34, 35, 37, 38, 40, 42, 44, 45, 47, 49, 51, 53, 55, 56, 58, 60, 62, 64, 67, 68, 71, 74, 77, 79, 83, 85, 88, 91, 94, 96, 100
Offset: 0

Views

Author

Ilya Gutkovskiy, Jan 11 2017

Keywords

Comments

Number of partitions of n into centered pentagonal numbers (A005891).

Examples

			a(12) = 3 because we have [6, 6], [6, 1, 1, 1, 1, 1, 1] and [1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1].
		

Crossrefs

Programs

  • Maple
    h:= proc(n) option remember; `if`(n<0, 0, (t->
          `if`(((t+1)*5*t+2)/2>n, t-1, t))(1+h(n-1)))
        end:
    b:= proc(n, i) option remember; `if`(n=0, 1, `if`(i<0, 0,
          b(n, i-1)+(t-> b(n-t, min(i, h(n-t))))(((i+1)*5*i+2)/2)))
        end:
    a:= n-> b(n, h(n)):
    seq(a(n), n=0..100);  # Alois P. Heinz, Dec 28 2018
  • Mathematica
    nmax = 88; CoefficientList[Series[Product[1/(1 - x^(5 k (k + 1)/2 + 1)), {k, 0, nmax}], {x, 0, nmax}], x]

Formula

G.f.: Product_{k>=0} 1/(1 - x^(5*k*(k+1)/2+1)).

A279012 Expansion of Product_{k>=1} 1/(1 - x^(k*(5*k-3)/2)).

Original entry on oeis.org

1, 1, 1, 1, 1, 1, 1, 2, 2, 2, 2, 2, 2, 2, 3, 3, 3, 3, 4, 4, 4, 5, 5, 5, 5, 6, 6, 6, 7, 7, 7, 7, 8, 8, 9, 10, 11, 11, 11, 12, 12, 13, 14, 15, 15, 15, 16, 16, 17, 18, 19, 19, 20, 21, 22, 24, 25, 26, 26, 27, 28, 29, 31, 32, 33, 33, 34, 35, 37, 39, 41, 42, 43, 45, 46, 48, 50, 52, 53, 54, 56, 58, 60, 62, 64, 65, 67, 69, 72, 75, 78
Offset: 0

Views

Author

Ilya Gutkovskiy, Dec 03 2016

Keywords

Comments

Number of partitions of n into nonzero heptagonal numbers (A000566).

Examples

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

Crossrefs

Programs

  • Maple
    h:= proc(n) option remember; `if`(n<1, 0, (t->
          `if`(t*(5*t-3)/2>n, t-1, t))(1+h(n-1)))
        end:
    b:= proc(n, i) option remember; `if`(n=0, 1, `if`(i<1, 0,
          b(n, i-1)+(t-> b(n-t, min(i, h(n-t))))(i*(5*i-3)/2)))
        end:
    a:= n-> b(n, h(n)):
    seq(a(n), n=0..100);  # Alois P. Heinz, Dec 28 2018
  • Mathematica
    nmax=90; CoefficientList[Series[Product[1/(1 - x^(k (5 k - 3)/2)), {k, 1, nmax}], {x, 0, nmax}], x]

Formula

G.f.: Product_{k>=1} 1/(1 - x^(k*(5*k-3)/2)).

A279041 Expansion of Product_{k>=1} 1/(1 - x^(k*(3*k-2))).

Original entry on oeis.org

1, 1, 1, 1, 1, 1, 1, 1, 2, 2, 2, 2, 2, 2, 2, 2, 3, 3, 3, 3, 3, 4, 4, 4, 5, 5, 5, 5, 5, 6, 6, 6, 7, 7, 7, 7, 7, 8, 8, 8, 10, 10, 11, 11, 11, 12, 12, 12, 14, 14, 15, 15, 15, 16, 16, 16, 18, 18, 19, 19, 19, 21, 21, 22, 24, 25, 26, 26, 26, 28, 28, 29, 31, 32, 33, 33, 33, 35, 35, 36, 39, 40, 42, 42, 43, 45, 46, 47, 50, 51, 53
Offset: 0

Views

Author

Ilya Gutkovskiy, Dec 04 2016

Keywords

Comments

Number of partitions of n into nonzero octagonal numbers (A000567).

Examples

			a(9) = 2 because we have [8, 1] and [1, 1, 1, 1, 1, 1, 1, 1, 1].
		

Crossrefs

Programs

  • Maple
    h:= proc(n) option remember; `if`(n<1, 0, (t->
          `if`(t*(3*t-2)>n, t-1, t))(1+h(n-1)))
        end:
    b:= proc(n, i) option remember; `if`(n=0, 1, `if`(i<1, 0,
          b(n, i-1)+(t-> b(n-t, min(i, h(n-t))))(i*(3*i-2))))
        end:
    a:= n-> b(n, h(n)):
    seq(a(n), n=0..100);  # Alois P. Heinz, Dec 28 2018
  • Mathematica
    nmax=90; CoefficientList[Series[Product[1/(1 - x^(k (3 k - 2))), {k, 1, nmax}], {x, 0, nmax}], x]

Formula

G.f.: Product_{k>=1} 1/(1 - x^(k*(3*k-2))).

A290942 Number of partitions of n into distinct generalized pentagonal numbers (A001318).

Original entry on oeis.org

1, 1, 1, 1, 0, 1, 1, 2, 2, 1, 1, 0, 2, 2, 2, 3, 1, 2, 2, 2, 3, 2, 4, 3, 3, 3, 2, 5, 4, 5, 4, 2, 3, 3, 6, 6, 5, 5, 4, 5, 7, 8, 8, 7, 6, 6, 6, 8, 9, 9, 9, 7, 8, 9, 9, 11, 10, 11, 11, 10, 12, 10, 14, 15, 14, 14, 11, 13, 13, 17, 17, 14, 15, 14, 17, 20, 19, 20, 20, 20, 21, 20, 21, 21, 25, 26, 23, 22, 21, 24, 27
Offset: 0

Views

Author

Ilya Gutkovskiy, Aug 14 2017

Keywords

Examples

			a(15) = 3 because we have [15], [12, 2, 1] and [7, 5, 2, 1].
		

Crossrefs

Programs

  • Mathematica
    nmax = 90; CoefficientList[Series[Product[(1 + x^(k (3 k - 1)/2)) (1 + x^(k (3 k + 1)/2)), {k, 1, nmax}], {x, 0, nmax}], x]

Formula

G.f.: Product_{k>=1} (1 + x^(k*(3*k-1)/2))*(1 + x^(k*(3*k+1)/2)).

A305355 Expansion of Product_{k>=1} (1 - x^(k*(3*k-1)/2)).

Original entry on oeis.org

1, -1, 0, 0, 0, -1, 1, 0, 0, 0, 0, 0, -1, 1, 0, 0, 0, 1, -1, 0, 0, 0, -1, 1, 0, 0, 0, 1, -1, 0, 0, 0, 0, 0, 1, -2, 1, 0, 0, -1, 2, -1, 0, 0, 0, 0, 0, 1, -1, 0, 0, -1, 0, 1, 0, 0, 1, 0, -1, 0, 0, 0, -1, 2, -1, 0, 0, 0, -1, 0, 0, 1, 0, 1, 0, 0, -1, 0, -1, 1, 0, 0, 1
Offset: 0

Views

Author

Seiichi Manyama, May 31 2018

Keywords

Crossrefs

Product_{k>=1} (1 - x^(k*((m-2)*k-(m-4))/2)): A292518 (m=3), A276516 (m=4), this sequence (m=5).

Programs

  • Maple
    seq(coeff(series(mul(1-x^(k*(3*k-1)/2),k=1..n), x,n+1),x,n),n=0..140); # Muniru A Asiru, May 31 2018

A332007 Number of compositions (ordered partitions) of n into distinct pentagonal numbers.

Original entry on oeis.org

1, 1, 0, 0, 0, 1, 2, 0, 0, 0, 0, 0, 1, 2, 0, 0, 0, 2, 6, 0, 0, 0, 1, 2, 0, 0, 0, 2, 6, 0, 0, 0, 0, 0, 2, 7, 2, 0, 0, 6, 26, 6, 0, 0, 0, 0, 0, 2, 6, 0, 0, 1, 8, 24, 0, 0, 2, 8, 6, 0, 0, 0, 6, 26, 6, 0, 0, 0, 6, 30, 25, 2, 0, 2, 30, 122, 6, 0, 6, 24
Offset: 0

Views

Author

Ilya Gutkovskiy, Feb 04 2020

Keywords

Examples

			a(18) = 6 because we have [12, 5, 1], [12, 1, 5], [5, 12, 1], [5, 1, 12], [1, 12, 5] and [1, 5, 12].
		

Crossrefs

A296237 Expansion of Product_{k>0} 1/(1 - x^(k*(3*k+1)/2)).

Original entry on oeis.org

1, 0, 1, 0, 1, 0, 1, 1, 1, 1, 1, 1, 1, 1, 2, 2, 2, 2, 2, 2, 2, 3, 3, 3, 3, 3, 4, 3, 5, 4, 6, 4, 6, 5, 6, 6, 7, 7, 7, 7, 9, 8, 10, 9, 11, 10, 11, 12, 12, 13, 13, 14, 15, 14, 17, 16, 19, 18, 20, 20, 21, 22, 23, 24, 25, 25, 28, 27, 30, 29, 33, 32, 35, 35, 37, 38, 39
Offset: 0

Views

Author

Seiichi Manyama, Dec 09 2017

Keywords

Comments

Integer partitions into second or "negative" pentagonal numbers (A005449) .

Crossrefs

Programs

  • Mathematica
    nmax = 100; CoefficientList[Series[Product[1/(1 - x^(k*(3*k+1)/2)), {k, 1, nmax}], {x, 0, nmax}], x] (* Vaclav Kotesovec, Dec 10 2017 *)
  • PARI
    N=66; x='x+O('x^N); Vec(1/prod(k=1, N, (1-x^(k*(3*k+1)/2))))
Showing 1-10 of 10 results.