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.

A213853 Rectangular array: (row n) = b**c, where b(h) = h, c(h) = binomial(2*n-4+2*h,n-2+h), n>=1, h>=1, and ** = convolution.

Original entry on oeis.org

1, 4, 2, 13, 10, 6, 42, 38, 32, 20, 141, 136, 128, 110, 70, 492, 486, 476, 452, 392, 252, 1767, 1760, 1748, 1718, 1638, 1428, 924, 6474, 6466, 6452, 6416, 6316, 6036, 5280, 3432, 24051, 24042, 24026, 23984, 23864, 23514, 22506, 19734, 12870
Offset: 1

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Author

Clark Kimberling, Jul 05 2012

Keywords

Comments

Row 1, (1,2,3,4,5,...)**(1,2,6,20,70,...):
Row 2, (1,2,3,4,5,...)**(2,6,20,70,252,...):
Row 3, (1,2,3,4,5,...)**(6,20,70,252,...):
For a guide to related arrays, see A213500.

Examples

			Northwest corner (the array is read by falling antidiagonals):
  1    4     13     42     141
  2    10    38     136    486
  6    32    128    476    1748
  20   110   452    1718   6416
  70   392   1638   6316   23864
		

Crossrefs

Cf. A213500.

Programs

  • Mathematica
    b[n_]:=n;c[n_]:=Binomial[2n-2,n-1]
    t[n_,k_]:=Sum[b[k-i]c[n+i],{i,0,k-1}]
    TableForm[Table[t[n,k],{n,1,10},{k,1,10}]]
    Flatten[Table[t[n-k+1,k],{n,12},{k,n,1,-1}]]
    r[n_]:=Table[t[n,k],{k,1,20}] (* A213853 *)