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.

A382833 Square array read by antidiagonals: T(n,k) is the number of distinct sum-of-powers vectors (Sum_{x in X} x^m, 0 <= m <= k) for subsets X of {0, ..., n-1}; n, k >= 0.

Original entry on oeis.org

1, 1, 2, 1, 2, 3, 1, 2, 4, 4, 1, 2, 4, 8, 5, 1, 2, 4, 8, 15, 6, 1, 2, 4, 8, 16, 26, 7, 1, 2, 4, 8, 16, 32, 42, 8, 1, 2, 4, 8, 16, 32, 64, 64, 9, 1, 2, 4, 8, 16, 32, 64, 126, 93, 10, 1, 2, 4, 8, 16, 32, 64, 128, 247, 130, 11, 1, 2, 4, 8, 16, 32, 64, 128, 256, 476, 176, 12
Offset: 0

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Author

Pontus von Brömssen, Apr 10 2025

Keywords

Examples

			Array begins:
  n\k|  0   1     2     3     4
  ---+-------------------------
   0 |  1   1     1     1     1
   1 |  2   2     2     2     2
   2 |  3   4     4     4     4
   3 |  4   8     8     8     8
   4 |  5  15    16    16    16
   5 |  6  26    32    32    32
   6 |  7  42    64    64    64
   7 |  8  64   126   128   128
   8 |  9  93   247   256   256
   9 | 10 130   476   512   512
  10 | 11 176   908  1024  1024
  11 | 12 232  1682  2048  2048
  12 | 13 299  3067  4080  4096
  13 | 14 378  5364  8128  8192
  14 | 15 470  9132 16128 16384
  15 | 16 576 14948 31992 32768
  16 | 17 697 23635 63163 65520
For n = 4, k = 1, there is only one pair of subsets of {0, 1, 2, 3} for which the two subsets have the same number of elements (sum of 0th powers) and the same sum (sum of 1st powers), namely {0, 3}, {1, 2}. Hence, T(4,1) = 2^4-1 = 15.
		

Crossrefs

Cf. A000027 (column k=0), A000125 (column k=1), A382383, A382832.

Formula

T(n,k) <= 2^n with equality if and only if n < A382832(k).