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.

A298671 Number of ordered ways of writing n^3 as a sum of n nonnegative cubes.

Original entry on oeis.org

1, 1, 2, 3, 4, 5, 146, 4207, 26329, 257721, 3556495, 42685181, 631230381, 9409600499, 142557084957, 2781352245050, 52598395446786, 950288577530017, 20768368026768594, 448759012546543804, 9652848877533217174, 235179507693424886403, 5756272592837812726164, 140920987987840184113287
Offset: 0

Views

Author

Ilya Gutkovskiy, Jan 24 2018

Keywords

Examples

			a(3) = 3 because we have [27, 0, 0], [0, 27, 0] and [0, 0, 27].
		

Crossrefs

Programs

  • Mathematica
    Table[SeriesCoefficient[Sum[x^k^3, {k, 0, n}]^n, {x, 0, n^3}], {n, 0, 23}]

Formula

a(n) = [x^(n^3)] (Sum_{k>=0} x^(k^3))^n.

A291700 Number of ways of writing n as a sum of n nonnegative cubes.

Original entry on oeis.org

1, 1, 1, 1, 1, 1, 1, 1, 9, 73, 361, 1321, 3961, 10297, 24025, 51481, 103081, 196521, 368425, 720937, 1589161, 4069801, 11511721, 33341353, 94142313, 253860201, 650564201, 1588228228, 3716917597, 8418378043, 18699454621, 41451042556, 93508305513, 218218347865, 530189399785
Offset: 0

Views

Author

Ilya Gutkovskiy, Aug 30 2017

Keywords

Crossrefs

Main diagonal of A290054.

Programs

  • Mathematica
    Table[SeriesCoefficient[Sum[x^k^3, {k, 0, n}]^n, {x, 0, n}], {n, 0, 34}]

Formula

a(n) = [x^n] (Sum_{k>=0} x^(k^3))^n.

A363779 Square array T(n,k), n >= 0, k >= 0, read by antidiagonals, where column k is the expansion of 1/(Sum_{j>=0} x^(j^3))^k.

Original entry on oeis.org

1, 1, 0, 1, -1, 0, 1, -2, 1, 0, 1, -3, 3, -1, 0, 1, -4, 6, -4, 1, 0, 1, -5, 10, -10, 5, -1, 0, 1, -6, 15, -20, 15, -6, 1, 0, 1, -7, 21, -35, 35, -21, 7, -1, 0, 1, -8, 28, -56, 70, -56, 28, -8, 0, 0, 1, -9, 36, -84, 126, -126, 84, -36, 7, 1, 0, 1, -10, 45, -120, 210, -252, 210, -120, 42, -4, -2, 0
Offset: 0

Views

Author

Seiichi Manyama, Jun 21 2023

Keywords

Examples

			Square array begins:
  1,  1,  1,   1,   1,    1,    1, ...
  0, -1, -2,  -3,  -4,   -5,   -6, ...
  0,  1,  3,   6,  10,   15,   21, ...
  0, -1, -4, -10, -20,  -35,  -56, ...
  0,  1,  5,  15,  35,   70,  126, ...
  0, -1, -6, -21, -56, -126, -252, ...
  0,  1,  7,  28,  84,  210,  462, ...
		

Crossrefs

Columns k=0..3 give A000007, A323633, A363776, A363777.
Main diagonal gives A363781.

Formula

T(0,k) = 1; T(n,k) = -(k/n) * Sum_{j=1..n} A363783(j) * T(n-j,k).

A290429 Square array A(n,k), n>=0, k>=0, read by antidiagonals, where column k is the expansion of (Sum_{j>=0} x^(j*(j+1)*(j+2)/6))^k.

Original entry on oeis.org

1, 1, 0, 1, 1, 0, 1, 2, 0, 0, 1, 3, 1, 0, 0, 1, 4, 3, 0, 1, 0, 1, 5, 6, 1, 2, 0, 0, 1, 6, 10, 4, 3, 2, 0, 0, 1, 7, 15, 10, 5, 6, 0, 0, 0, 1, 8, 21, 20, 10, 12, 3, 0, 0, 0, 1, 9, 28, 35, 21, 21, 12, 0, 1, 0, 0, 1, 10, 36, 56, 42, 36, 30, 4, 3, 0, 1, 0, 1, 11, 45, 84, 78, 63, 61, 20, 6, 3, 2, 0, 0, 1, 12, 55, 120, 135, 112, 112, 60, 15, 12, 3, 2, 0, 0
Offset: 0

Views

Author

Ilya Gutkovskiy, Jul 31 2017

Keywords

Comments

A(n,k) is the number of ways of writing n as a sum of k tetrahedral (or triangular pyramidal) numbers (A000292).

Examples

			Square array begins:
1,  1,  1,  1,   1,   1,  ...
0,  1,  2,  3,   4,   5,  ...
0,  0,  1,  3,   6,  10,  ...
0,  0,  0,  1,   4,  10,  ...
0,  1,  2,  3,   5,  10,  ...
0,  0,  2,  6,  12,  21,  ...
		

Crossrefs

Cf. A000007 (column 0), A023533 (column 1), A282172 (column 5).
Main diagonal gives A303170.
Similar to, but different from, A045847.

Programs

  • Mathematica
    Table[Function[k, SeriesCoefficient[Sum[x^(i (i + 1) (i + 2)/6), {i, 0, n}]^k, {x, 0, n}]][j - n], {j, 0, 13}, {n, 0, j}] // Flatten

Formula

G.f. of column k: (Sum_{j>=0} x^(j*(j+1)*(j+2)/6))^k.

A302019 Expansion of 1/(1 - x*Sum_{k>=0} x^(k^3)).

Original entry on oeis.org

1, 1, 2, 3, 5, 8, 13, 21, 34, 56, 91, 149, 243, 397, 648, 1058, 1727, 2819, 4602, 7512, 12263, 20018, 32678, 53344, 87080, 142151, 232050, 378803, 618366, 1009433, 1647819, 2689933, 4391101, 7168122, 11701387, 19101580, 31181804, 50901806, 83093134, 135642908, 221426218, 361460624
Offset: 0

Views

Author

Ilya Gutkovskiy, Mar 30 2018

Keywords

Crossrefs

Antidiagonal sums of A290054.

Programs

  • Mathematica
    nmax = 41; CoefficientList[Series[1/(1 - x Sum[x^k^3, {k, 0, nmax}]), {x, 0, nmax}], x]

Formula

G.f.: 1/(1 - x*Sum_{k>=0} x^(k^3)).
a(0) = 1; a(n) = Sum_{k=1..n} A010057(k-1)*a(n-k).

A303169 a(n) = [x^(n^3)] (1/(1 - x))*(Sum_{k>=0} x^(k^3))^n.

Original entry on oeis.org

1, 2, 6, 30, 241, 2093, 23059, 276056, 3657901, 51751598, 792918670, 13031054778, 228632547574, 4247832219975, 83138970732860, 1710953260292025, 36844216654753387, 827664913984323748, 19363023028132371129, 470436686367280495474, 11843579175327033093769
Offset: 0

Views

Author

Ilya Gutkovskiy, Apr 19 2018

Keywords

Comments

Number of nonnegative solutions to (x_1)^3 + (x_2)^3 + ... + (x_n)^3 <= n^3.

Crossrefs

Programs

  • Mathematica
    Table[SeriesCoefficient[1/(1 - x) Sum[x^k^3, {k, 0, n}]^n, {x, 0, n^3}], {n, 0, 20}]

A303484 Square array A(n,k), n >= 0, k >= 0, read by antidiagonals: A(n,k) = [x^(n^3)] (1/(1 - x))*(Sum_{j>=0} x^(j^3))^k.

Original entry on oeis.org

1, 1, 1, 1, 2, 1, 1, 3, 3, 1, 1, 4, 6, 4, 1, 1, 5, 11, 11, 5, 1, 1, 6, 20, 30, 18, 6, 1, 1, 7, 37, 84, 66, 26, 7, 1, 1, 8, 70, 237, 241, 115, 37, 8, 1, 1, 9, 135, 662, 853, 500, 200, 50, 9, 1, 1, 10, 264, 1780, 2847, 2093, 1012, 302, 63, 10, 1, 1, 11, 520, 4536, 9033, 8451, 4914, 1769, 441, 80, 11, 1
Offset: 0

Views

Author

Ilya Gutkovskiy, Apr 24 2018

Keywords

Comments

A(n,k) is the number of nonnegative solutions to (x_1)^3 + (x_2)^3 + ... + (x_k)^3 <= n^3.

Examples

			Square array begins:
1,  1,   1,    1,    1,     1,  ...
1,  2,   3,    4,    5,     6,  ...
1,  3,   6,   11,   20,    37,  ...
1,  4,  11,   30,   84,   237,  ...
1,  5,  18,   66,  241,   853,  ...
1,  6,  26,  115,  500,  2093,  ...
		

Crossrefs

Columns k=0..4 give A000012, A000027, A224214, A224215.
Main diagonal gives A303169.

Programs

  • Mathematica
    Table[Function[k, SeriesCoefficient[1/(1 - x) Sum[x^i^3, {i, 0, n}]^k, {x, 0, n^3}]][j - n], {j, 0, 11}, {n, 0, j}] // Flatten
Showing 1-7 of 7 results.