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.

A127446 Triangle T(n,k) = n*A051731(n,k) read by rows.

Original entry on oeis.org

1, 2, 2, 3, 0, 3, 4, 4, 0, 4, 5, 0, 0, 0, 5, 6, 6, 6, 0, 0, 6, 7, 0, 0, 0, 0, 0, 7, 8, 8, 0, 8, 0, 0, 0, 8, 9, 0, 9, 0, 0, 0, 0, 0, 9, 10, 10, 0, 0, 10, 0, 0, 0, 0, 10, 11, 0, 0, 0, 0, 0, 0, 0, 0, 0, 11, 12, 12, 12, 12, 0, 12, 0, 0, 0, 0, 0, 12, 13, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 13, 14, 14, 0, 0, 0, 0, 14
Offset: 1

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Author

Gary W. Adamson, Jan 14 2007

Keywords

Comments

Replace the 1's in row n of A051731 with n's.
T(n,k) is the sum of the k's in the partitions of n into equal parts. - Omar E. Pol, Nov 25 2019

Examples

			First few rows of the triangle:
  1;
  2, 2;
  3, 0, 3;
  4, 4, 0, 4;
  5, 0, 0, 0, 5;
  6, 6, 6, 0, 0, 6;
  7, 0, 0, 0, 0, 0, 7;
  ...
For n = 6 the partitions of 6 into equal parts are [6], [3,3], [2,2,2], [1,1,1,1,1,1], so the sum of the k's are [6, 6, 6, 0, 0, 6] respectively, equaling the 6th row of triangle. - _Omar E. Pol_, Nov 25 2019
		

Crossrefs

Cf. A038040 (row sums), A051731, A126988, A244051, A328362.

Programs

  • Haskell
    a127446 n k = a127446_tabl !! (n-1) !! (k-1)
    a127446_row n = a127446_tabl !! (n-1)
    a127446_tabl = zipWith (\v ws -> map (* v) ws) [1..] a051731_tabl
    -- Reinhard Zumkeller, Jan 21 2014
  • Maple
    A127446 := proc(n,k) if n mod k = 0 then n; else 0; fi; end: for n from 1 to 20 do for k from 1 to n do printf("%d,",A127446(n,k)) ; od: od: # R. J. Mathar, May 08 2009
  • Mathematica
    Flatten[Table[If[Mod[n, k] == 0, n, 0], {n, 20}, {k, n}]] (* Vincenzo Librandi, Nov 02 2016 *)

Formula

T(n,k) = k*A126988(n,k). - Omar E. Pol, Nov 25 2019

Extensions

Edited and extended by R. J. Mathar, May 08 2009