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.

Showing 1-3 of 3 results.

A045530 Convolution of A000108 (Catalan numbers) with A020922.

Original entry on oeis.org

1, 23, 310, 3195, 27866, 216566, 1546028, 10338515, 65635570, 399429602, 2346750900, 13384232030, 74417751940, 404759481420, 2159510136408, 11327603405955, 58528412321250, 298354368109930, 1502525977613540
Offset: 0

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Also convolution of A045505 with A000984 (central binomial coefficients); also convolution of A045492 with A000302 (powers of 4).

Programs

  • Magma
    R:=PowerSeriesRing(Rationals(), 40); Coefficients(R!( (Sqrt(1-4*x) +4*x-1)/(2*x*(1-4*x)^6) )); // G. C. Greubel, Jan 13 2020
    
  • Maple
    seq(coeff(series((sqrt(1-4*x) +4*x-1)/(2*x*(1-4*x)^6), x, n+1), x, n), n = 0..40); # G. C. Greubel, Jan 13 2020
  • Mathematica
    CoefficientList[Series[(Sqrt[1-4*x] +4*x-1)/(2*x*(1-4*x)^6), {x,0,40}], x] (* G. C. Greubel, Jan 13 2020 *)
  • PARI
    my(x='x+O('x^40)); Vec( (sqrt(1-4*x) +4*x-1)/(2*x*(1-4*x)^6) ) \\ G. C. Greubel, Jan 13 2020
    
  • Sage
    def A045530_list(prec):
        P. = PowerSeriesRing(ZZ, prec)
        return P( (sqrt(1-4*x) +4*x-1)/(2*x*(1-4*x)^6) ).list()
    A045530_list(40) # G. C. Greubel, Jan 13 2020

Formula

a(n) = binomial(n+6, 5)*(A000984(n+6)/A000984(5) - 5*4^(n+1)/(n+6))/2, A000984(n) = binomial(2*n, n).
G.f. c(x)/(1-4*x)^(11/2), where c(x) = g.f. for Catalan numbers.

A046527 A triangle related to A000108 (Catalan) and A000302 (powers of 4).

Original entry on oeis.org

1, 1, 1, 2, 5, 1, 5, 22, 9, 1, 14, 93, 58, 13, 1, 42, 386, 325, 110, 17, 1, 132, 1586, 1686, 765, 178, 21, 1, 429, 6476, 8330, 4746, 1477, 262, 25, 1, 1430, 26333, 39796, 27314, 10654, 2525, 362, 29, 1, 4862, 106762, 185517, 149052, 69930, 20754, 3973, 478, 33, 1
Offset: 0

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Examples

			Triangle begins as:
     1;
     1,      1;
     2,      5,      1;
     5,     22,      9,      1;
    14,     93,     58,     13,     1;
    42,    386,    325,    110,    17,     1;
   132,   1586,   1686,    765,   178,    21,    1;
   429,   6476,   8330,   4746,  1477,   262,   25,   1;
  1430,  26333,  39796,  27314, 10654,  2525,  362,  29,  1;
  4862, 106762, 185517, 149052, 69930, 20754, 3973, 478, 33,  1;
		

Crossrefs

Column sequences are: A000108 (k=0), A000346 (k=1), A018218 (k=2), A042941 (k=3), A042985 (k=4), A045505 (k=5), A045622 (k=6).
Row sums: A046814.

Programs

  • Magma
    A046527:= func< n,k | k eq 0 select Catalan(n) else (1/2)*Binomial(n, k-1)*(4^(n-k+1) - Binomial(2*n, n)/(k*Catalan(k-1))) >;
    [A046527(n,k): k in [0..n], n in [0..12]]; // G. C. Greubel, Jul 28 2024
    
  • Mathematica
    T[n_, k_]:= If[k==0, CatalanNumber[n], (1/2)*Binomial[n,k-1]*(4^(n-k+ 1) -Binomial[2*n,n]/Binomial[2*(k-1),k-1])];
    Table[T[n,k], {n,0,12}, {k,0,n}]//Flatten (* G. C. Greubel, Jul 28 2024 *)
  • SageMath
    def A046527(n,k):
        if k==0: return catalan_number(n)
        else: return (1/2)*binomial(n, k-1)*(4^(n-k+1) - binomial(2*n, n)/binomial(2*(k-1), k-1))
    flatten([[A046527(n,k) for k in range(n+1)] for n in range(13)]) # G. C. Greubel, Jul 28 2024

Formula

T(n, k) = binomial(n, k-1)*( 4^(n-k+1) - binomial(2*n, n)/binomial(2*(k-1), k-1) )/2, for n >= k >= 0, with T(n, 0) = A000108(n).
G.f. for column k: c(x)*(x/(1-4*x))^m, where c(x) = g.f. for Catalan numbers (A000108).

A045622 Convolution of A000108 (Catalan numbers) with A045543.

Original entry on oeis.org

1, 25, 362, 3973, 36646, 299530, 2238676, 15613741, 103054094, 650194974, 3950996556, 23257207714, 133217073276, 745218012084, 4083224828328, 21966983072637, 116268166691358, 606474982072982, 3122157367765788
Offset: 1

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Comments

Also convolution of A045530 with A000984 (central binomial coefficients); also convolution of A045505 with A000302 (powers of 4).

Programs

  • Magma
    R:=PowerSeriesRing(Rationals(), 40); Coefficients(R!( (1-Sqrt(1-4*x))/(2*(1-4*x)^6) )); // G. C. Greubel, Jan 13 2020
    
  • Maple
    seq(coeff(series((1-sqrt(1-4*x))/(2*(1-4*x)^6), x, n+1), x, n), n = 0..40); # G. C. Greubel, Jan 13 2020
  • Mathematica
    CoefficientList[Series[(1-Sqrt[1-4*x])/(2*x*(1-4*x)^6), {n,0,40}], x] (* G. C. Greubel, Jan 13 2020 *)
  • PARI
    my(x='x+O('x^40)); Vec((1-sqrt(1-4*x))/(2*(1-4*x)^6)) \\ G. C. Greubel, Jan 13 2020
    
  • Sage
    def A045622_list(prec):
        P. = PowerSeriesRing(ZZ, prec)
        return P( (1-sqrt(1-4*x))/(2*(1-4*x)^6) ).list()
    A045622_list(40) # G. C. Greubel, Jan 13 2020

Formula

a(n) = binomial(n+6, 5)*(4^(n+1) - A000984(n+6)/A000984(5))/2, A000984(n) = binomial(2*n, n).
G.f.: x*c(x)/(1-4*x)^6, where c(x) = g.f. for Catalan numbers.
Showing 1-3 of 3 results.