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

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

Offset

0,3

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.

Links

Table of n, a(n) for n=0..12.

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

Mathematica

Table[(-1)^n QBinomial[2n, n, 2]/(2^(n+1) - 1), {n, 0, 20}] (* Vladimir Reshetnikov, Sep 16 2016 *)

Prog

(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) )

Crossrefs

Cf. A135951, A135950, A022166.

Sequence in context: A000365 A209471 A012784 * A015030 A270071 A047052

Adjacent sequences: A136094 A136095 A136096 * A136098 A136099 A136100

Keyword

sign

Author

Paul D. Hanna, Dec 13 2007

Status

approved