A107052 Denominators of coefficients that satisfy: 4^n = Sum_{k=0..n} c(k)*x^k for n>=0, where c(k) = A107051(k)/a(k).

1, 1, 4, 4, 256, 800000, 9600000, 7906012800000, 129532113715200000, 206516028134758809600000, 2581450351684485120000000000, 736517912438453927556570808320000000000

Offset

0,3

Links

Table of n, a(n) for n=0..11.

Formula

A107051(n)/a(n) = Sum_{k=0..n} T(n, k)*4^k where T(n, k) = A107045(n, k)/A107046(n, k) = [A079901^-1](n, k) (matrix inverse of A079901).

Example

4^0 = 1;
4^1 = 1 + (3)*1;
4^2 = 1 + (3)*2 + (9/4)*2^2;
4^3 = 1 + (3)*3 + (9/4)*3^2 + (5/4)*3^3;
4^4 = 1 + (3)*4 + (9/4)*4^2 + (5/4)*4^3 + (127/256)*4^4.
Initial coefficients are:
A107051/A107052 = {1, 3, 9/4, 5/4, 127/256, 124273/800000,
385829/9600000, 70009765747/7906012800000,
220026935042111/129532113715200000, ...}.

Prog

(PARI) {a(n)=denominator(sum(k=0, n, 4^k*(matrix(n+1, n+1, r, c, if(r>=c, (r-1)^(c-1)))^-1)[n+1, k+1]))}

Crossrefs

Cf. A107051, A107045/A107046, A107047/A107048 (y=2), A107049/A107050 (y=3), A107053/A107054 (y=5).

Sequence in context: A080509 A063439 A218050 * A000790 A068556 A078243

Adjacent sequences: A107049 A107050 A107051 * A107053 A107054 A107055

Keyword

nonn,frac

Author

Paul D. Hanna, May 10 2005

Status

approved