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.

A237596 Convolution triangle of A000958(n+1).

Original entry on oeis.org

1, 1, 1, 3, 2, 1, 8, 7, 3, 1, 24, 22, 12, 4, 1, 75, 73, 43, 18, 5, 1, 243, 246, 156, 72, 25, 6, 1, 808, 844, 564, 283, 110, 33, 7, 1, 2742, 2936, 2046, 1092, 465, 158, 42, 8, 1, 9458, 10334, 7449, 4178, 1906, 714, 217, 52, 9, 1, 33062, 36736, 27231, 15904, 7670, 3096, 1043, 288, 63, 10, 1
Offset: 0

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Author

Philippe Deléham, Feb 09 2014

Keywords

Comments

Riordan array (f(x)/x, f(x)) where f(x) is the g.f. of A000958.
Reversal of A236918.
Row sums are A109262(n+1).
Diagonal sums are A033297(n+2).

Examples

			Triangle begins:
    1;
    1,   1;
    3,   2,   1;
    8,   7,   3,   1;
   24,  22,  12,   4,   1;
   75,  73,  43,  18,   5,  1;
  243, 246, 156,  72,  25,  6, 1;
  808, 844, 564, 283, 110, 33, 7, 1;
  ...
		

Crossrefs

Columns give A000958, A114495.
Cf. A033297 (diagonal sums), A109262 (row sums), A236918 (row reversal).

Programs

  • Maple
    # Uses function PMatrix from A357368. Adds column 1,0,0,0,... to the left.
    PMatrix(10, n -> A000958(n)); # Peter Luschny, Oct 19 2022
  • Mathematica
    P[n_, x_]:= P[n, x]= If[n==0, 1, Sum[(j/(2*n-j))*Binomial[2*n-j, n-j]*Fibonacci[j, x], {j,0,n}]];
    T[n_, k_] := Coefficient[P[n+1, x], x, k];
    Table[T[n, k], {n,0,13}, {k,0,n}]//Flatten (* G. C. Greubel, Jun 14 2022 *)
  • SageMath
    def f(n,x): return sum( binomial(n-j-1, j)*x^(n-2*j-1) for j in (0..(n-1)//2) )
    def p(n,x):
        if (n==0): return 1
        else: return sum( (j/(2*n-j))*binomial(2*n-j, n-j)*f(j, x) for j in (0..n) )
    def A237596(n,k): return ( p(n+1,x) ).series(x, n+1).list()[k]
    flatten([[A237596(n,k) for k in (0..n)] for n in (0..12)]) # G. C. Greubel, Jun 14 2022

Formula

G.f. for the column k-1: ((1-sqrt(1-4*x))^k/(1+sqrt(1-4*x) + 2*x)^k)/x.
Sum_{k=0..n} T(n,k) = A109262(n+1).
From G. C. Greubel, Jun 14 2022: (Start)
T(n, k) = coefficient of [x^k]( p(n+1, x) ), where p(n, x) = Sum_{j=0..n} (j/(2*n-j))*binomial(2*n-j, n-j)*Fibonacci(j, x) with p(0, x) = 1 and Fibonacci(n, x) are the Fibonacci polynomials.
T(n, k) = A236918(n, n-k). (End)