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.

A015033 q-Catalan numbers (binomial version) for q=3.

Original entry on oeis.org

1, 1, 10, 847, 627382, 4138659802, 244829520301060, 130191700295480695111, 622829375926755523108996006, 26812578369717035183629988539429726, 10387976772168532331015929118843873280496300
Offset: 0

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Author

Keywords

Crossrefs

Cf. A015030 (q=2).

Programs

  • Magma
    q:=3; [1] cat [((1-q)/(1-q^(n+1)))*(&*[(1-q^(2*n-k))/(1-q^(k+1)): k in [0..n-1]]): n in [1..20]]; // G. C. Greubel, Nov 11 2018
  • Mathematica
    Table[2 QBinomial[2n, n, 3]/(3^(n+1) - 1), {n, 0, 20}]
  • PARI
    q=3; for(n=0, 20, print1(((1-q)/(1-q^(n+1)))*prod(k=0,n-1, (1-q^(2*n-k))/(1-q^(k+1))), ", ")) \\ G. C. Greubel, Nov 11 2018
    

Formula

a(n) = binomial(2*n, n, q)/(n+1)_q, where binomial(n,m,q) is the q-binomial coefficient, with q=3.
a(n) = ((1-q)/(1-q^(n+1)))*Product_{k=0..(n-1)} (1-q^(2*n-k))/(1-q^(k+1)), with q=3. - G. C. Greubel, Nov 11 2018

A015034 q-Catalan numbers (binomial version) for q=4.

Original entry on oeis.org

1, 1, 17, 4433, 18245201, 1197172898385, 1255709588423576145, 21068918017101222558779985, 5655752483351603939678821837720145, 24291387778773301588924456932322615789898321
Offset: 0

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Author

Keywords

Crossrefs

Cf. A015030 (q=2).

Programs

  • Magma
    q:=4; [1] cat [((1-q)/(1-q^(n+1)))*(&*[(1-q^(2*n-k))/(1-q^(k+1)): k in [0..n-1]]): n in [1..20]]; // G. C. Greubel, Nov 11 2018
  • Mathematica
    Table[3*QBinomial[2 n, n, 4]/(4^(n + 1) - 1), {n, 0, 20}] (* G. C. Greubel, Nov 11 2018 *)
  • PARI
    q=4; for(n=0, 20, print1(((1-q)/(1-q^(n+1)))*prod(k=0,n-1, (1-q^(2*n-k))/(1-q^(k+1))), ", ")) \\ G. C. Greubel, Nov 11 2018
    

Formula

a(n) = binomial(2*n, n, q)/(n+1)_q, where binomial(n,m,q) is the q-binomial coefficient, with q=4.
a(n) = ((1-q)/(1-q^(n+1)))*Product_{k=0..(n-1)} (1-q^(2*n-k))/(1-q^(k+1)), with q=4. - G. C. Greubel, Nov 11 2018

A136097 a(n) = A135951(n) /[(2^(n+1)-1) * 2^(n*(n-1)/2)].

Original entry on oeis.org

1, -1, 5, -93, 6477, -1733677, 1816333805, -7526310334829, 124031223014725741, -8152285307423733458541, 2140200604371078953284092525, -2245805993494514875022552272042605, 9423041917569791458584837551185555483245
Offset: 0

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Author

Paul D. Hanna, Dec 13 2007

Keywords

Comments

A135951 is the central terms of A135950; A135950 is the matrix inverse of A022166; A022166 is the triangle of Gaussian binomial coefficients [n,k] for q = 2.

Crossrefs

Programs

  • Mathematica
    Table[(-1)^n QBinomial[2n, n, 2]/(2^(n+1) - 1), {n, 0, 20}] (* Vladimir Reshetnikov, Sep 16 2016 *)
  • PARI
    a(n)=local(q=2,A=matrix(2*n+1,2*n+1,n,k,if(n>=k,if(n==1 || k==1, 1, prod(j=n-k+1, n-1, 1-q^j)/prod(j=1, k-1, 1-q^j))))^-1); A[2*n+1,n+1]/( (q^(n+1)-1)/(q-1) * q^(n*(n-1)/2) )

Formula

Conjecture: the n-th central term of the matrix inverse of the triangle of Gaussian binomial coefficients in q is divisible by [(q^(n+1)-1)/(q-1) * q^(n*(n-1)/2)] for n>=0 and integer q > 1.
a(n) = (-1)^n * A015030(n) where A015030 is 2-Catalan numbers. - Michael Somos, Jan 10 2023

A384437 Square array A(n,k), n >= 0, k >= 0, read by antidiagonals downwards, where A(n,k) is the n-th q-Catalan number for q=k.

Original entry on oeis.org

1, 1, 1, 1, 1, 1, 1, 1, 2, 1, 1, 1, 5, 5, 1, 1, 1, 10, 93, 14, 1, 1, 1, 17, 847, 6477, 42, 1, 1, 1, 26, 4433, 627382, 1733677, 132, 1, 1, 1, 37, 16401, 18245201, 4138659802, 1816333805, 429, 1, 1, 1, 50, 48205, 256754526, 1197172898385, 244829520301060, 7526310334829, 1430, 1
Offset: 0

Views

Author

Seiichi Manyama, May 29 2025

Keywords

Examples

			Square array begins:
  1,  1,       1,          1,             1,               1, ...
  1,  1,       1,          1,             1,               1, ...
  1,  2,       5,         10,            17,              26, ...
  1,  5,      93,        847,          4433,           16401, ...
  1, 14,    6477,     627382,      18245201,       256754526, ...
  1, 42, 1733677, 4138659802, 1197172898385, 100333200992026, ...
		

Crossrefs

Main diagonal gives A384282.

Programs

  • PARI
    a(n, k) = if(k==1, binomial(2*n, n)/(n+1), (1-k)/(1-k^(n+1))*prod(j=0, n-1, (1-k^(2*n-j))/(1-k^(j+1))));
    
  • Sage
    from sage.combinat.q_analogues import q_catalan_number
    def a(n, k): return q_catalan_number(n, k)

Formula

A(n,k) = q_binomial(2*n, n, k)/q_binomial(n+1, 1, k).
Showing 1-4 of 4 results.