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.

A238709 Triangular array: t(n,k) = number of partitions p = {x(1) >= x(2) >= ... >= x(k)} such that min(x(j) - x(j-1)) = k.

Original entry on oeis.org

1, 1, 1, 3, 0, 1, 4, 1, 0, 1, 7, 1, 1, 0, 1, 10, 2, 0, 1, 0, 1, 16, 2, 1, 0, 1, 0, 1, 22, 3, 1, 1, 0, 1, 0, 1, 32, 4, 2, 0, 1, 0, 1, 0, 1, 44, 5, 2, 1, 0, 1, 0, 1, 0, 1, 62, 6, 3, 1, 1, 0, 1, 0, 1, 0, 1, 83, 8, 3, 2, 0, 1, 0, 1, 0, 1, 0, 1, 113, 10, 4, 2, 1
Offset: 1

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Author

Clark Kimberling, Mar 03 2014

Keywords

Comments

The first two columns are essentially A047967 and A238708. Counting the top row as row 2, the sum of numbers in row n is A000041(n) - 1.

Examples

			row 2:  1
row 3:  1 ... 1
row 4:  3 ... 0 ... 1
row 5:  4 ... 1 ... 0 ... 1
row 6:  7 ... 1 ... 1 ... 0 ... 1
row 7:  10 .. 2 ... 0 ... 1 ... 0 ... 1
row 8:  16 .. 2 ... 1 ... 0 ... 1 ... 0 ... 1
row 9:  22 .. 3 ... 1 ... 1 ... 0 ... 1 ... 0 ... 1
Let m = min(x(j) - x(j-1)); then for row 5, the 4 partitions with m = 0 are 311, 221, 2111, 11111; the 1 partition with m = 1 is 32, and the 1 partition with m = 3 is 41.
		

Crossrefs

Programs

  • Mathematica
    z = 25; p[n_, k_] := p[n, k] = IntegerPartitions[n][[k]]; m[n_, k_] := m[n, k] = Min[-Differences[p[n, k]]]; c[n_] := Table[m[n, h], {h, 1, PartitionsP[n]}]; v = Table[Count[c[n], h], {n, 2, z}, {h, 0, n - 2}]; Flatten[v]
    TableForm[v]