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.

A176282 Triangle T(n,k) = 1 + A000330(n) - A000330(k) - A000330(n-k), read by rows.

Original entry on oeis.org

1, 1, 1, 1, 4, 1, 1, 9, 9, 1, 1, 16, 21, 16, 1, 1, 25, 37, 37, 25, 1, 1, 36, 57, 64, 57, 36, 1, 1, 49, 81, 97, 97, 81, 49, 1, 1, 64, 109, 136, 145, 136, 109, 64, 1, 1, 81, 141, 181, 201, 201, 181, 141, 81, 1, 1, 100, 177, 232, 265, 276, 265, 232, 177, 100, 1
Offset: 0

Views

Author

Roger L. Bagula, Apr 14 2010

Keywords

Comments

Not summing squares but summing integers implied by the definition (i.e., not using A000330 but A000217) gives A077028.
Row sums = {1, 2, 6, 20, 55, 126, 252, 456, 765, 1210, 1826, ...} = (n+1)*(n+2)*(n^2-2*n+3)/6.

Examples

			Triangle begins as:
  1;
  1,   1;
  1,   4,   1;
  1,   9,   9,   1;
  1,  16,  21,  16,   1;
  1,  25,  37,  37,  25,   1;
  1,  36,  57,  64,  57,  36,   1;
  1,  49,  81,  97,  97,  81,  49,   1;
  1,  64, 109, 136, 145, 136, 109,  64,   1;
  1,  81, 141, 181, 201, 201, 181, 141,  81,   1;
  1, 100, 177, 232, 265, 276, 265, 232, 177, 100, 1;
		

Crossrefs

Cf. A077028.

Programs

  • GAP
    Flat(List([0..12], n-> List([0..n], k-> 1 + k*(n+1)*(n-k) ))); # G. C. Greubel, Nov 24 2019
  • Magma
    [1 + k*(n+1)*(n-k): k in [0..n], n in [0..12]]; // G. C. Greubel, Nov 24 2019
    
  • Maple
    seq(seq(1 + k*(n+1)*(n-k), k=0..n), n=0..12); # G. C. Greubel, Nov 24 2019
  • Mathematica
    (* Set of sequences q=1..10. This sequence is q=2. *)
    f[n_, k_, q_]:= f[n, k, q] = 1 + Sum[i^q, {i,0,n}] - Sum[i^q, {i,0,k}] - Sum[i^q, {i,0,n-k}]; Table[Flatten[Table[f[n, k, q], {n,0,12}, {k,0,n}]], {q,1,10}]
    (* Second program *)
    Table[1 + k*(n+1)*(n-k), {n,0,12}, {k,0,n}]//Flatten (* G. C. Greubel, Nov 24 2019 *)
  • PARI
    T(n,k) = 1 + k*(n+1)*(n-k); \\ G. C. Greubel, Nov 24 2019
    
  • Sage
    [[1 + k*(n+1)*(n-k) for k in (0..n)] for n in (0..12)] # G. C. Greubel, Nov 24 2019
    

Formula

T(n,k) = T(n,n-k).
T(n,k) = 1 + k*(n+1)*(n-k). - G. C. Greubel, Nov 24 2019

Extensions

Edited by R. J. Mathar, May 03 2013