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 1-7 of 7 results.

A282582 Number of compositions (ordered partitions) of n into tetrahedral (or triangular pyramidal) numbers (A000292).

Original entry on oeis.org

1, 1, 1, 1, 2, 3, 4, 5, 7, 10, 15, 21, 29, 40, 57, 81, 114, 159, 223, 314, 444, 625, 878, 1233, 1736, 2445, 3441, 4838, 6804, 9573, 13473, 18957, 26668, 37514, 52780, 74264, 104488, 147000, 206808, 290961, 409369, 575955, 810314, 1140029, 1603924, 2256603, 3174867, 4466763, 6284339, 8841533, 12439323
Offset: 0

Views

Author

Ilya Gutkovskiy, Feb 19 2017

Keywords

Examples

			a(8) = 7 because we have [4, 4], [4, 1, 1, 1, 1], [1, 4, 1, 1, 1], [1, 1, 4, 1, 1], [1, 1, 1, 4, 1], [1, 1, 1, 1, 4] and [1, 1, 1, 1, 1, 1, 1, 1].
		

Crossrefs

Programs

  • Mathematica
    nmax = 50; CoefficientList[Series[1/(1 - Sum[x^(k (k + 1) (k + 2)/6), {k, 1, nmax}]), {x, 0, nmax}], x]
  • PARI
    Vec(1/(1 - sum(k=1, 50, x^(k*(k + 1)*(k + 2)/6)) + O(x^51))) \\ Indranil Ghosh, Mar 15 2017

Formula

G.f.: 1/(1 - Sum_{k>=1} x^(k*(k+1)*(k+2)/6)).

A350205 a(n) is the smallest positive integer which can be represented as the sum of distinct nonzero tetrahedral numbers in exactly n ways, or 0 if no such integer exists.

Original entry on oeis.org

1, 35, 140, 175, 225, 290, 374, 400, 430, 455, 539, 540, 630, 655, 690, 595, 680, 760, 795, 715, 770, 865, 830, 945, 875, 980, 935, 960, 1080, 990, 970, 1075, 995, 1160, 1165, 1110, 1050, 1170, 1135, 1220, 1190, 1350, 1305, 1285, 1389, 1310, 1320, 1360, 1355, 1340
Offset: 1

Views

Author

Ilya Gutkovskiy, Dec 19 2021

Keywords

Crossrefs

A281081 Expansion of Product_{k>=0} (1 + x^(3*k*(k+1)/2+1)).

Original entry on oeis.org

1, 1, 0, 0, 1, 1, 0, 0, 0, 0, 1, 1, 0, 0, 1, 1, 0, 0, 0, 1, 1, 0, 0, 1, 1, 0, 0, 0, 0, 1, 1, 1, 1, 1, 1, 1, 1, 0, 0, 0, 0, 1, 1, 0, 0, 1, 2, 1, 0, 0, 2, 2, 0, 0, 1, 1, 1, 1, 0, 0, 2, 2, 0, 0, 2, 3, 1, 0, 1, 2, 1, 0, 0, 0, 1, 2, 1, 1, 2, 2, 1, 1, 1, 1, 1, 1, 1, 2, 2, 1, 1, 1, 1, 1, 1, 2, 3, 2, 1, 2, 3, 1, 0, 0, 1, 2
Offset: 0

Views

Author

Ilya Gutkovskiy, Jan 14 2017

Keywords

Comments

Number of partitions of n into distinct centered triangular numbers (A005448).

Examples

			a(46) = 2 because we have [46] and [31, 10, 4, 1].
		

Crossrefs

Programs

  • Mathematica
    nmax = 105; CoefficientList[Series[Product[1 + x^(3 k (k + 1)/2 + 1), {k, 0, nmax}], {x, 0, nmax}], x]

Formula

G.f.: Product_{k>=0} (1 + x^(3*k*(k+1)/2+1)).

A298857 Number of partitions of the n-th tetrahedral number into distinct tetrahedral numbers.

Original entry on oeis.org

1, 1, 1, 1, 1, 2, 2, 1, 2, 3, 2, 5, 5, 10, 12, 17, 15, 22, 30, 56, 65, 72, 92, 172, 219, 299, 368, 478, 810, 1055, 1508, 1778, 2277, 3815, 5214, 7103, 8615, 11614, 18079, 24428, 33704, 42877, 56639, 85597, 116984, 159179, 199356, 268965, 400612, 545674, 740356, 950897, 1261597, 1842307
Offset: 0

Views

Author

Ilya Gutkovskiy, Jan 27 2018

Keywords

Examples

			a(5) = 2 because fifth tetrahedral number is 35 and we have [35] and [20, 10, 4, 1].
		

Crossrefs

Programs

  • Mathematica
    Table[SeriesCoefficient[Product[1 + x^(k (k + 1) (k + 2)/6), {k, 1, n}], {x, 0, n (n + 1) (n + 2)/6}], {n, 0, 53}]

Formula

a(n) = [x^A000292(n)] Product_{k>=1} (1 + x^A000292(k)).
a(n) = A279278(A000292(n)).

A298246 Expansion of Product_{k>=1} (1 + x^(k*(k+1)*(2*k+1)/6)).

Original entry on oeis.org

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

Views

Author

Ilya Gutkovskiy, Jan 15 2018

Keywords

Comments

Number of partitions of n into distinct square pyramidal numbers.

Examples

			a(91) = 2 because we have [91] and [55, 30, 5, 1].
		

Crossrefs

Programs

  • Mathematica
    nmax = 104; CoefficientList[Series[Product[1 + x^(k (k + 1) (2 k + 1)/6), {k, 1, nmax}], {x, 0, nmax}], x]

Formula

G.f.: Product_{k>=1} (1 + x^A000330(k)).

A331919 Number of compositions (ordered partitions) of n into distinct tetrahedral numbers.

Original entry on oeis.org

1, 1, 0, 0, 1, 2, 0, 0, 0, 0, 1, 2, 0, 0, 2, 6, 0, 0, 0, 0, 1, 2, 0, 0, 2, 6, 0, 0, 0, 0, 2, 6, 0, 0, 6, 25, 2, 0, 0, 2, 6, 0, 0, 0, 0, 2, 6, 0, 0, 6, 24, 0, 0, 0, 0, 2, 7, 2, 0, 6, 26, 6, 0, 0, 0, 6, 26, 6, 0, 24, 126, 24, 0, 0, 0, 0, 2, 6, 0, 0, 6, 24, 0, 0, 1, 2, 6, 24, 2, 6, 24
Offset: 0

Views

Author

Ilya Gutkovskiy, Feb 01 2020

Keywords

Examples

			a(15) = 6 because we have [10, 4, 1], [10, 1, 4], [4, 10, 1], [4, 1, 10], [1, 10, 4] and [1, 4, 10].
		

Crossrefs

Programs

  • Maple
    N:= 200: # for a(0)..a(N)
    G:= mul(1+t*x^(i*(i+1)*(i+2)/6), i=1..floor((6*N)^(1/3))):
    F:= proc(n) local R, k, v;
      R:= coeff(G, x, n);
      add(k!*coeff(R, t, k), k=1..degree(R, t))
    end proc:
    F(0):= 1:
    map(F, [$0..N]); # Robert Israel, Feb 03 2020
  • Mathematica
    M = 100;
    G = Product[1 + t x^(i(i+1)(i+2)/6), {i, 1, Floor[(6M)^(1/3)]}];
    F[n_] := Module[{R, k, v}, R = Coefficient[G, x, n]; Sum[k! Coefficient[R, t, k], {k, 1, Exponent[R, t]}]];
    F[0] = 1;
    F /@ Range[0, M] (* Jean-François Alcover, Jun 20 2020, after Robert Israel *)

A298247 Expansion of Product_{k>=1} (1 - x^(k*(k+1)*(k+2)/6)).

Original entry on oeis.org

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

Views

Author

Ilya Gutkovskiy, Jan 15 2018

Keywords

Comments

The difference between the number of partitions of n into an even number of distinct tetrahedral numbers and the number of partitions of n into an odd number of distinct tetrahedral numbers.

Crossrefs

Programs

  • Mathematica
    nmax = 104; CoefficientList[Series[Product[1 - x^(k (k + 1) (k + 2)/6), {k, 1, nmax}], {x, 0, nmax}], x]

Formula

G.f.: Product_{k>=1} (1 - x^A000292(k)).
Showing 1-7 of 7 results.