cp's OEIS Frontend

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).

%I A107052 #4 Mar 30 2012 18:36:46
%S A107052 1,1,4,4,256,800000,9600000,7906012800000,129532113715200000,
%T A107052 206516028134758809600000,2581450351684485120000000000,
%U A107052 736517912438453927556570808320000000000
%N 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).
%F A107052 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).
%e A107052 4^0 = 1;
%e A107052 4^1 = 1 + (3)*1;
%e A107052 4^2 = 1 + (3)*2 + (9/4)*2^2;
%e A107052 4^3 = 1 + (3)*3 + (9/4)*3^2 + (5/4)*3^3;
%e A107052 4^4 = 1 + (3)*4 + (9/4)*4^2 + (5/4)*4^3 + (127/256)*4^4.
%e A107052 Initial coefficients are:
%e A107052 A107051/A107052 = {1, 3, 9/4, 5/4, 127/256, 124273/800000,
%e A107052 385829/9600000, 70009765747/7906012800000,
%e A107052 220026935042111/129532113715200000, ...}.
%o A107052 (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]))}
%Y A107052 Cf. A107051, A107045/A107046, A107047/A107048 (y=2), A107049/A107050 (y=3), A107053/A107054 (y=5).
%K A107052 nonn,frac
%O A107052 0,3
%A A107052 _Paul D. Hanna_, May 10 2005