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 1-4 of 4 results.

A042985 Convolution of A000108 (Catalan numbers) with A038846.

Original entry on oeis.org

1, 17, 178, 1477, 10654, 69930, 428772, 2496813, 13962982, 75582078, 398302268, 2052354850, 10375356460, 51596749300, 252953904072, 1224672639357, 5863899363510, 27801377704310, 130648178243660, 609082400931158
Offset: 0

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Keywords

Comments

Also convolution of A045724 with A000984 (central binomial coefficients); also convolution of A042941 with A000302 (powers of 4).

Programs

  • Magma
    m:=20; R:=PowerSeriesRing(Rationals(), m); Coefficients(R!( (1-Sqrt(1-4*x))/(2*x*(1-4*x)^4) )); // G. C. Greubel, Feb 17 2019
    
  • Mathematica
    CoefficientList[Series[(1-Sqrt[1-4*x])/(2*x*(1-4*x)^4), {x, 0, 20}], x] (* G. C. Greubel, Feb 17 2019 *)
  • PARI
    my(x='x+O('x^20)); Vec((1-sqrt(1-4*x))/(2*x*(1-4*x)^4)) \\ G. C. Greubel, Feb 17 2019
    
  • Sage
    ((1-sqrt(1-4*x))/(2*x*(1-4*x)^4)).series(x, 20).coefficients(x, sparse=False) # G. C. Greubel, Feb 17 2019

Formula

a(n) = binomial(n+4, 3)*(4^(n+1) - A000984(n+4)/A000984(3))/2, where A000984(n) = binomial(2*n, n).
G.f.: (1 - sqrt(1-4*x))/(2*x*(1-4*x)^4).
D-finite with recurrence: n*(n+1)*a(n) -2*n*(4*n+13)*a(n-1) +8*(n+3)*(2*n+5)*a(n-2)=0. - R. J. Mathar, Jan 28 2020

A045724 Convolution of Catalan numbers A000108 with A020918.

Original entry on oeis.org

1, 15, 142, 1083, 7266, 44758, 259356, 1435347, 7663898, 39761282, 201483204, 1001098462, 4891910100, 23565178380, 112118316088, 527674017411, 2459747256138, 11368724035210, 52145629874100, 237541552456362
Offset: 0

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Keywords

Comments

Also convolution of A001700 with A038845; also convolution of A029887 with A000302 (powers of 4); also convolution of A042941 with A000984 (central binomial coefficients).

Crossrefs

Programs

  • Magma
    [(Binomial(n+5,4)*Catalan(n+4) -5*4^(n+1)*Binomial(n+3,2))/10: n in [0..40]]; // G. C. Greubel, Jul 19 2024
    
  • Mathematica
    Table[(Binomial[n+5,4]*CatalanNumber[n+4] -5*4^(n+1)*Binomial[n+3,2] )/10, {n,0,40}] (* G. C. Greubel, Jul 19 2024 *)
  • SageMath
    [(binomial(n+5,4)*catalan_number(n+4) - 5*4^(n+1)*binomial(n+3,2))/10 for n in range(41)] # G. C. Greubel, Jul 19 2024

Formula

a(n) = binomial(n+4, 3)*A000984(n+4)/(2*A000984(3)) - (n+3)*(n+2)*4^n, where A000984(n) = binomial(2*n, n),
G.f.: c(x)/(1-4*x)^(7/2) = (2 - c(x))/(1-4*x)^4, 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).

A090299 Table T(n,k), n>=0 and k>=0, read by antidiagonals : the k-th column given by the k-th polynomial K_k related to A090285.

Original entry on oeis.org

1, 1, 1, 2, 3, 1, 5, 10, 5, 1, 14, 35, 22, 7, 1, 42, 126, 93, 38, 9, 1, 132, 462, 386, 187, 58, 11, 1, 429, 1716, 1586, 874, 325, 82, 13, 1, 1430, 6435, 6476, 3958, 1686, 515, 110, 15, 1, 4862, 24310, 26333, 17548, 8330, 2934, 765, 142, 17, 1
Offset: 0

Views

Author

Philippe Deléham, Jan 25 2004

Keywords

Comments

Read as a number triangle, this is the Riordan array (c(x),x/sqrt(1-4x)) where c(x) is the g.f. of A000108. - Paul Barry, May 16 2005

Examples

			row n=0 : 1, 1, 2, 5, 14, 42, 132, 429, ... see A000108.
row n=1 : 1, 3, 10, 35, 126, 462, 1716, 6435, ... see A001700.
row n=2 : 1, 5, 22, 93, 386, 1586, 6476, ... see A000346.
row n=3 : 1, 7, 38, 187, 874, 3958, 17548, ... see A000531.
row n=4 : 1, 9, 58, 325, 1686, 8330, 39796, ... see A018218.
		

Crossrefs

Other rows : A029887, A042941, A045724, A042985, A045492. Columns : A000012, A005408. Row n is the convolution of the row (n-j) with A000984, A000302, A002457, A002697 (first term omitted), A002802, A038845, A020918, A038846, A020920 for j=1, 2, ..9 respectively.

Formula

T(n, k) = K_k(n)= Sum_{j>=0} A090285(k, j)*2^j*binomial(n, j). T(n, 1) = 2*n+1. T(n, 2) = 2*A028387(n).

Extensions

Corrected by Alford Arnold, Oct 18 2006
Showing 1-4 of 4 results.