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.

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A176078 Triangle, read by rows, T(n, k) = (2*n)!/((n-k)! * k!)^2 - (2*n)!/(n!)^2 + 1.

Original entry on oeis.org

1, 1, 1, 1, 19, 1, 1, 161, 161, 1, 1, 1051, 2451, 1051, 1, 1, 6049, 24949, 24949, 6049, 1, 1, 32341, 206977, 368677, 206977, 32341, 1, 1, 164737, 1510081, 4200769, 4200769, 1510081, 164737, 1, 1, 810811, 10077211, 40347451, 63050131, 40347451, 10077211, 810811, 1
Offset: 0

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Author

Roger L. Bagula, Apr 08 2010

Keywords

Comments

Row sums are: {1, 2, 21, 324, 4555, 61998, 847315, 11751176, 165521079, 2363418210, 34132747231, ...}.

Examples

			Triangle begins as:
  1;
  1,      1;
  1,     19,       1;
  1,    161,     161,       1;
  1,   1051,    2451,    1051,       1;
  1,   6049,   24949,   24949,    6049,       1;
  1,  32341,  206977,  368677,  206977,   32341,      1;
  1, 164737, 1510081, 4200769, 4200769, 1510081, 164737, 1;
		

Crossrefs

Programs

  • GAP
    B:=Binomial;; Flat(List([0..10], n-> List([0..n], k-> B(2*n,n)*(B(n,k)^2 -1)+1 ))); # G. C. Greubel, Nov 27 2019
  • Magma
    B:=Binomial; [B(2*n,n)*(B(n,k)^2 -1)+1: k in [0..n], n in [0..10]]; // G. C. Greubel, Nov 27 2019
    
  • Maple
    b:=binomial; T(n,k):=b(2*n,n)*(b(n,k)^2 -1)+1; seq(seq(T(n,k), k=0..n), n=0..10); # G. C. Greubel, Nov 27 2019
  • Mathematica
    T[n_, k_] = (2*n)!/((n-k)!*k!)^2 - (2*n)!/(n!)^2 + 1; Table[T[n, k], {n, 0, 10}, (k, 0, n)]//Flatten
  • PARI
    b=binomial; T(n,k) = b(2*n,n)*(b(n,k)^2 -1)+1; \\ G. C. Greubel, Nov 27 2019
    
  • Sage
    b=binomial; [[b(2*n,n)*(b(n,k)^2 -1)+1 for k in (0..n)] for n in (0..10)] # G. C. Greubel, Nov 27 2019
    

Formula

T(n, k) = (2*n)!/((n-k)! * k!)^2 - (2*n)!/(n!)^2 + 1.
T(n, k) = binomial(2*n,n)*( binomial(n,k)^2 - 1) + 1. - G. C. Greubel, Nov 27 2019
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