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.

A123019 Triangle of coefficients of (1 - x)^n*b(x/(1 - x),n), where b(x,n) is the Morgan-Voyce polynomial related to A085478.

Original entry on oeis.org

1, 1, 1, 1, -1, 1, 3, -4, 1, 1, 6, -9, 3, 1, 10, -15, 3, 3, -1, 1, 15, -20, -6, 18, -8, 1, 1, 21, -21, -35, 60, -30, 5, 1, 28, -14, -98, 145, -70, 5, 5, -1, 1, 36, 6, -210, 279, -100, -45, 45, -12, 1, 1, 45, 45, -384, 441, -21, -280, 210, -63, 7, 1, 55, 110
Offset: 0

Views

Author

Roger L. Bagula and Gary W. Adamson, Sep 24 2006

Keywords

Comments

The n-th row consists of the coefficients in the expansion of Sum_{j=0..n} A085478(n,j)*x^j*(1 - x)^(n - j).

Examples

			Triangle begins:
    1;
    1;
    1,  1,  -1;
    1,  3,  -4,    1;
    1,  6,  -9,    3;
    1, 10, -15,    3,   3,   -1;
    1, 15, -20,   -6,  18,   -8,    1;
    1, 21, -21,  -35,  60,  -30,    5;
    1, 28, -14,  -98, 145,  -70,    5,   5,   -1;
    1, 36,   6, -210, 279, -100,  -45,  45,  -12, 1;
    1, 45,  45, -384, 441,  -21, -280, 210,  -63, 7;
    1, 55, 110, -627, 561,  385, -973, 665, -189, 7, 7, -1;
    ... reformatted and extended. - _Franck Maminirina Ramaharo_, Oct 09 2018
		

Crossrefs

Programs

  • Mathematica
    Table[CoefficientList[Sum[Binomial[n+k, n-k]*x^k*(1-x)^(n-k), {k, 0, n}], x], {n, 0, 10}]//Flatten
  • Maxima
    A085478(n, k) := binomial(n + k, 2*k)$
    P(x, n) := expand(sum(A085478(n, j)*x^j*(1 - x)^(n - j),j,0,n))$
    T(n, k) := ratcoef(P(x, n), x, k)$
    tabf(nn) := for n:0 thru nn do print(makelist(T(n, k), k, 0, hipow(P(x, n), x))); /* Franck Maminirina Ramaharo, Oct 09 2018 */
    
  • Sage
    def p(n,x): return sum( binomial(n+j, 2*j)*x^j*(1-x)^(n-j) for j in (0..n) )
    def T(n): return ( p(n,x) ).full_simplify().coefficients(sparse=False)
    flatten([T(n) for n in (0..12)]) # G. C. Greubel, Jul 15 2021

Formula

G.f.: (1 - (1 - x)*y)/(1 + (x - 2)*y + (x - 1)^2*y^2). - Vladeta Jovovic, Dec 14 2009
From Franck Maminirina Ramaharo, Oct 10 2018: (Start)
Row n = coefficients in the expansion of (1/(2*sqrt((4 - 3*x)*x)))*((sqrt((4 - 3*x)*x) + x)*((2 - x + sqrt((4 - 3*x)*x))/2)^n + (sqrt((4 - 3*x)*x) - x)*((2 - x - sqrt((4 - 3*x)*x))/2)^n).
E.g.f.: (1/(2*sqrt((4 - 3*x)*x)))*((sqrt((4 - 3*x)*x) + x)*exp(y*(2 - x + sqrt((4 - 3*x)*x))/2) + (sqrt((4 - 3*x)*x) - x)*exp(y*(2 - x - sqrt((4 - 3*x)*x))/2)).
T(n,1) = A000217(n-1). (End)

Extensions

Edited, new name, and offset corrected by Franck Maminirina Ramaharo, Oct 09 2018