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.

A135221 Triangle A007318 + A000012(signed) - I, I = Identity matrix, read by rows.

Original entry on oeis.org

1, 0, 1, 2, 1, 1, 0, 4, 2, 1, 2, 3, 7, 3, 1, 0, 6, 9, 11, 4, 1, 2, 5, 16, 19, 16, 5, 1, 0, 8, 20, 36, 34, 22, 6, 1, 2, 7, 29, 55, 71, 55, 29, 7, 1, 0, 10, 35, 85, 125, 127, 83, 37, 8, 1, 2, 9, 46, 119, 211, 251, 211, 119, 46, 9, 1, 0, 12, 54, 166, 329, 463, 461, 331, 164, 56, 10, 1
Offset: 0

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Author

Gary W. Adamson, Nov 23 2007

Keywords

Comments

row sums = A051049: (1, 1, 4, 7, 16, 31, 64, ...).

Examples

			First few rows of the triangle:
  1;
  0, 1;
  2, 1,  1;
  0, 4,  2,  1;
  2, 3,  7,  3,  1;
  0, 6,  9, 11,  4,  1;
  2, 5, 16, 19, 16,  5,  1;
  0, 8, 20, 36, 34, 22,  6, 1;
  2, 7, 29, 55, 71, 55, 29, 7, 1;
...
		

Crossrefs

Programs

  • GAP
    T:= function(n,k)
        if k=n then return 1;
        else return Binomial(n,k) + (-1)^(n-k);
        fi; end;
    Flat(List([0..12], n-> List([0..n], k-> T(n,k) ))); # G. C. Greubel, Nov 20 2019
  • Magma
    T:= func< n,k | k eq n select 1 else Binomial(n,k) +(-1)^(n-k) >;
    [T(n,k): k in [0..n], n in [0..12]]; // G. C. Greubel, Nov 20 2019
    
  • Maple
    seq(seq( `if`(k=n, 1, binomial(n,k) + (-1)^(n-k)), k=0..n), n=0..12); # G. C. Greubel, Nov 20 2019
  • Mathematica
    T[n_, k_]:= T[n, k]= If[k==n, 1, Binomial[n, k] + (-1)^(n-k)] ;
    Table[T[n, k], {n, 0, 12}, {k, 0, n}]//Flatten (* G. C. Greubel, Nov 20 2019 *)
  • PARI
    T(n,k) = if(k==n, 1, binomial(n,k) + (-1)^(n-k)); \\ G. C. Greubel, Nov 20 2019
    
  • Sage
    def T(n, k):
        if (k==n): return 1
        else: return binomial(n,k) + (-1)^(n-k)
    [[T(n, k) for k in (0..n)] for n in (0..12)] # G. C. Greubel, Nov 20 2019
    

Formula

T(n,k) = A007318 + A000012(signed) - Identity matrix, where A000012(signed) = (1; -1,1; 1,-1,1; ...).
T(n,k) = (-1)^(n-k) + binomial(n,k), with T(n,n)=1. - G. C. Greubel, Nov 20 2019

Extensions

More terms added by G. C. Greubel, Nov 20 2019