A120999 Denominators of partial sums of Catalan numbers scaled by powers of 1/7^2 = 1/49.
1, 49, 2401, 117649, 823543, 40353607, 13841287201, 678223072849, 33232930569601, 1628413597910449, 79792266297612001, 558545864083284007, 27368747340080916343, 9387480337647754305649, 459986536544739960976801
Offset: 0
Examples
Rationals r(n): [1, 50/49, 2452/2401, 120153/117649, 841073/823543, 41212583/40353607, 14135916101/13841287201,...].
Formula
a(n)=denominator(r(n)) with r(n) := rI(p=2,n) = sum(C(k)/L(4)^(2*k),k=0..n), with Lucas L(4)=7 and C(k):=A000108(k) (Catalan). The rationals r(n) are given in lowest terms.
Comments