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.

A174102 Triangle read by rows: T(n, m) = floor(binomial(n+1, m)* binomial(n+2, m)/(2*m+2)), 1 <= m <= n.

Original entry on oeis.org

1, 3, 3, 5, 10, 5, 7, 25, 25, 7, 10, 52, 87, 52, 10, 14, 98, 245, 245, 98, 14, 18, 168, 588, 882, 588, 168, 18, 22, 270, 1260, 2646, 2646, 1260, 270, 22, 27, 412, 2475, 6930, 9702, 6930, 2475, 412, 27, 33, 605, 4537, 16335, 30492, 30492, 16335, 4537, 605, 33
Offset: 1

Views

Author

Roger L. Bagula, Mar 07 2010

Keywords

Comments

Row sums are {1, 6, 20, 64, 211, 714, 2430, 8396, 29390, 104004, 371448, 1337216, ...}.

Examples

			Triangle begins as:
   1;
   3,   3;
   5,  10,    5;
   7,  25,   25,    7;
  10,  52,   87,   52,   10;
  14,  98,  245,  245,   98,   14;
  18, 168,  588,  882,  588,  168,   18;
  22, 270, 1260, 2646, 2646, 1260,  270,  22;
  27, 412, 2475, 6930, 9702, 6930, 2475, 412, 27;
		

Crossrefs

Cf. A166454.
Cf. A011848 (right diagonal).

Programs

  • Magma
    [[Floor(Binomial(n+1, k)*Binomial(n+2, k)/(2*k+2)): k in [1..n]]: n in [1..12]]; // G. C. Greubel, Apr 13 2019
    
  • Mathematica
    T[n_, k_] = Floor[Binomial[n+1, k]*Binomial[n+2, k]/(2*(k+1))];
    Table[T[n, k], {n,1,12}, {k,1,n}]//Flatten (* modified by G. C. Greubel, Apr 13 2019 *)
  • PARI
    {T(n,k) = (binomial(n+1,k)*binomial(n+2,k)/(2*k+2))\1};
    for(n=1,12, for(k=1,n, print1(T(n,k), ", "))) \\ G. C. Greubel, Apr 13 2019
    
  • Sage
    [[floor(binomial(n+1,k)*binomial(n+2,k)/(2*k+2)) for k in (1..n)] for n in (1..12)] # G. C. Greubel, Apr 13 2019

Formula

T(n, m) = floor(binomial(n+1, m-1)*binomial(n+2, m-1)/(2*m)).

Extensions

Partially edited by Jon E. Schoenfield, Dec 02 2013
Edited by G. C. Greubel, Apr 13 2019