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 1-4 of 4 results.

A145515 Square array A(n,k), n>=0, k>=0, read by antidiagonals: A(n,k) is the number of partitions of k^n into powers of k.

Original entry on oeis.org

1, 1, 1, 1, 1, 1, 1, 2, 1, 1, 1, 2, 4, 1, 1, 1, 2, 5, 10, 1, 1, 1, 2, 6, 23, 36, 1, 1, 1, 2, 7, 46, 239, 202, 1, 1, 1, 2, 8, 82, 1086, 5828, 1828, 1, 1, 1, 2, 9, 134, 3707, 79326, 342383, 27338, 1, 1, 1, 2, 10, 205, 10340, 642457, 18583582, 50110484, 692004, 1, 1, 1, 2, 11, 298, 24901, 3649346, 446020582, 14481808030, 18757984046, 30251722, 1, 1
Offset: 0

Views

Author

Alois P. Heinz, Oct 11 2008

Keywords

Examples

			A(2,3) = 5, because there are 5 partitions of 3^2=9 into powers of 3: [1,1,1,1,1,1,1,1,1], [1,1,1,1,1,1,3], [1,1,1,3,3], [3,3,3], [9].
Square array A(n,k) begins:
  1,  1,   1,    1,     1,      1,  ...
  1,  1,   2,    2,     2,      2,  ...
  1,  1,   4,    5,     6,      7,  ...
  1,  1,  10,   23,    46,     82,  ...
  1,  1,  36,  239,  1086,   3707,  ...
  1,  1, 202, 5828, 79326, 642457,  ...
		

Crossrefs

Row n=3 gives: A189890(k+1).
Main diagonal gives: A145514.
Cf. A007318.

Programs

  • Maple
    b:= proc(n, j, k) local nn;
          nn:= n+1;
          if n<0  then 0
        elif j=0  or n=0 or k<=1 then 1
        elif j=1  then nn
        elif n>=j then (nn-j) *binomial(nn, j) *add(binomial(j, h)
                       /(nn-j+h) *b(j-h-1, j, k) *(-1)^h, h=0..j-1)
                  else b(n, j, k):= b(n-1, j, k) +b(k*n, j-1, k)
          fi
        end:
    A:= (n, k)-> b(1, n, k):
    seq(seq(A(n, d-n), n=0..d), d=0..13);
  • Mathematica
    b[n_, j_, k_] := Module[{nn = n+1}, Which[n < 0, 0, j == 0 || n == 0 || k <= 1, 1, j == 1, nn, n >= j, (nn-j)*Binomial[nn, j]*Sum[Binomial[j, h]/(nn-j+h)* b[j-h-1, j, k]*(-1)^h, {h, 0, j-1}], True, b[n, j, k] = b[n-1, j, k] + b[k*n, j-1, k] ] ]; a[n_, k_] := b[1, n, k]; Table[Table[a[n, d-n], {n, 0, d}], {d, 0, 13}] // Flatten (* Jean-François Alcover, Dec 12 2013, translated from Maple *)

Formula

See program.
For k>1: A(n,k) = [x^(k^n)] 1/Product_{j>=0} (1-x^(k^j)).

Extensions

Edited by Alois P. Heinz, Jan 12 2011

A196879 Square array A(n,k), n>=0, k>=0, read by antidiagonals: A(n,k) is the number of partitions of n^k into powers of k.

Original entry on oeis.org

1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 4, 1, 1, 1, 1, 3, 10, 1, 1, 1, 1, 6, 23, 36, 1, 1, 1, 1, 9, 72, 132, 94, 1, 1, 1, 1, 16, 335, 1086, 729, 284, 1, 1, 1, 1, 36, 2220, 15265, 15076, 3987, 692, 1, 1, 1, 1, 85, 19166, 374160, 642457, 182832, 18687, 1828, 1, 1
Offset: 0

Views

Author

Alois P. Heinz, Oct 07 2011

Keywords

Examples

			A(2,3) = 3, because the number of partitions of 2^3=8 into powers of 3 is 3: [1,1,3,3], [1,1,1,1,1,3], [1,1,1,1,1,1,1,1].
Square array A(n,k) begins:
  1,  1,  1,   1,     1,      1,  ...
  1,  1,  1,   1,     1,      1,  ...
  1,  1,  4,   3,     6,      9,  ...
  1,  1, 10,  23,    72,    335,  ...
  1,  1, 36, 132,  1086,  15265,  ...
  1,  1, 94, 729, 15076, 642457,  ...
		

Crossrefs

Main diagonal gives: A145514.
Cf. A145515.

Programs

  • Maple
    b:= proc(n, j, k) local nn, r;
          if n<0 then 0
        elif j=0 then 1
        elif j=1 then n+1
        elif n
    				
  • Mathematica
    a[, 0] = a[, 1] = a[0, ] = a[1, ] = 1; a[n_, k_] := SeriesCoefficient[ 1/Product[ (1 - x^(k^j)), {j, 0, n}], {x, 0, n^k}]; Table[a[n - k, k], {n, 0, 10}, {k, n, 0, -1}] // Flatten (* Jean-François Alcover, Dec 09 2013 *)

Formula

For k>1: A(n,k) = [x^(n^k)] 1/Product_{j>=0}(1-x^(k^j)).

A331402 a(n) = [x^(n^n)] Product_{k>=1} 1 / (1 - x^(k^n)).

Original entry on oeis.org

1, 2, 5, 36, 1104, 140549, 82159688, 237700614212, 3591644060379486
Offset: 1

Views

Author

Ilya Gutkovskiy, Jan 16 2020

Keywords

Comments

Number of partitions of n^n into n-th powers.

Examples

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

Crossrefs

Diagonal of A259799.
Cf. A145514.

Formula

a(n) = A259799(n,n).

Extensions

a(8)-a(9) from Giovanni Resta, Jan 17 2020

A337990 Number of compositions (ordered partitions) of n^n into powers of n.

Original entry on oeis.org

1, 1, 6, 26426, 773527571233557154337704151068262296
Offset: 0

Views

Author

Ilya Gutkovskiy, Oct 06 2020

Keywords

Comments

The next term is too large to include.

Examples

			a(2) = 6 because 2^2 = 4 and we have [4], [2, 2], [2, 1, 1] (3 permutations), [1, 1, 1, 1] and 1 + 1 + 3 + 1 = 6.
		

Crossrefs

Programs

  • Mathematica
    Join[{1, 1}, Table[SeriesCoefficient[1/(1 - Sum[x^(n^k), {k, 0, n}]), {x, 0, n^n}], {n, 2, 4}]]

Formula

a(n) = [x^(n^n)] 1 / (1 - Sum_{k>=0} x^(n^k)), for n > 1.
Showing 1-4 of 4 results.