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 1-3 of 3 results.

A292745 Number A(n,k) of partitions of n with k sorts of part 1 which are introduced in ascending order; square array A(n,k), n>=0, k>=0, read by antidiagonals.

Original entry on oeis.org

1, 1, 0, 1, 1, 1, 1, 1, 2, 1, 1, 1, 3, 3, 2, 1, 1, 3, 6, 5, 2, 1, 1, 3, 7, 13, 7, 4, 1, 1, 3, 7, 19, 26, 11, 4, 1, 1, 3, 7, 20, 52, 54, 15, 7, 1, 1, 3, 7, 20, 62, 151, 108, 22, 8, 1, 1, 3, 7, 20, 63, 217, 442, 219, 30, 12, 1, 1, 3, 7, 20, 63, 232, 803, 1314, 439, 42, 14
Offset: 0

Views

Author

Alois P. Heinz, Sep 22 2017

Keywords

Examples

			A(3,2) = 6: 3, 21a, 1a1a1a, 1a1a1b, 1a1b1a, 1a1b1b.
Square array A(n,k) begins:
  1,  1,   1,    1,    1,    1,    1,    1,    1, ...
  0,  1,   1,    1,    1,    1,    1,    1,    1, ...
  1,  2,   3,    3,    3,    3,    3,    3,    3, ...
  1,  3,   6,    7,    7,    7,    7,    7,    7, ...
  2,  5,  13,   19,   20,   20,   20,   20,   20, ...
  2,  7,  26,   52,   62,   63,   63,   63,   63, ...
  4, 11,  54,  151,  217,  232,  233,  233,  233, ...
  4, 15, 108,  442,  803,  944,  965,  966,  966, ...
  7, 22, 219, 1314, 3092, 4158, 4425, 4453, 4454, ...
		

Crossrefs

Main diagonal gives A292503.

Programs

  • Maple
    f:= (n, k)-> add(Stirling2(n, j), j=0..k):
    b:= proc(n, i, k) option remember; `if`(n=0 or i<2,
          f(n, k), add(b(n-i*j, i-1, k), j=0..n/i))
        end:
    A:= (n, k)-> b(n$2, k):
    seq(seq(A(n, d-n), n=0..d), d=0..14);
  • Mathematica
    f[n_, k_] := Sum[StirlingS2[n, j], {j, 0, k}];
    b[n_, i_, k_] := b[n, i, k] = If[n == 0 || i < 2, f[n, k], Sum[b[n - i*j, i - 1, k], {j, 0, n/i}]];
    A[n_, k_] := b[n, n, k];
    Table[A[n, d - n], {d, 0, 14}, {n, 0, d}] // Flatten (* Jean-François Alcover, May 17 2018, translated from Maple *)

Formula

A(n,k) = Sum_{j=0..k} A292746(n,j).
A(n,k) = A(n,n) for all k >= n.

A320820 Number of partitions of n with exactly seven sorts of part 1 which are introduced in ascending order.

Original entry on oeis.org

1, 28, 463, 5909, 64479, 633796, 5786275, 50033463, 415225854, 3338335646, 26179143977, 201266007483, 1522856635641, 11374331041836, 84061202478127, 615860361908534, 4479596579257904, 32388729758708314, 233011769893620853, 1669336230635613631
Offset: 7

Views

Author

Alois P. Heinz, Oct 21 2018

Keywords

Crossrefs

Column k=7 of A292746.

Programs

  • Maple
    b:= proc(n, i, k) option remember; `if`(n=0 or i<2, add(
          Stirling2(n, j), j=0..k), add(b(n-i*j, i-1, k), j=0..n/i))
        end:
    a:= n-> (k-> b(n$2, k)-b(n$2, k-1))(7):
    seq(a(n), n=7..35);

Formula

a(n) = A320738(n) - A320737(n).

A320821 Number of partitions of n with exactly eight sorts of part 1 which are introduced in ascending order.

Original entry on oeis.org

1, 36, 751, 11917, 159815, 1912316, 21084803, 218711887, 2164920950, 20657703246, 191440769945, 1732792167043, 15385193971985, 134455882817716, 1159708265019855, 9893526482067374, 83627808435796896, 701411197245083482, 5844301347854288709, 48423747013469923303
Offset: 8

Views

Author

Alois P. Heinz, Oct 21 2018

Keywords

Crossrefs

Column k=8 of A292746.

Programs

  • Maple
    b:= proc(n, i, k) option remember; `if`(n=0 or i<2, add(
          Stirling2(n, j), j=0..k), add(b(n-i*j, i-1, k), j=0..n/i))
        end:
    a:= n-> (k-> b(n$2, k)-b(n$2, k-1))(8):
    seq(a(n), n=8..35);

Formula

a(n) = A320739(n) - A320738(n).
Showing 1-3 of 3 results.