A224680 a(n) = A224678(n^2).

1, 5, 49, 1117, 57181, 7086833, 2109733585, 1508630963069, 2591308566579217, 10691434112980070315, 105957942450483004330197, 2522387398320711543274084153, 144235039901139444727535460625985, 19811186631607253937472121882634566325

Offset

1,2

Comments

A224678 is the logarithmic derivative of A023361, where A023361(n) = number of compositions of n into positive triangular numbers.

Links

Table of n, a(n) for n=1..14.

Formula

Logarithmic derivative of A224681.

Example

L.g.f.: L(x) = x + 5*x^2/2 + 49*x^3/3 + 1117*x^4/4 + 57181*x^5/5 + 7086833*x^6/6 +...
where
exp(L(x)) = 1 + x + 3*x^2 + 19*x^3 + 300*x^4 + 11768*x^5 + 1193594*x^6 +...+ A224681(n)*x^n +...

Prog

(PARI) {a(n)=n^2*polcoeff(-log(1-sum(r=1, 2*n+1, x^(r*(r+1)/2)+x*O(x^(n^2)))), n^2)}
for(n=1, 20, print1(a(n), ", "))

Crossrefs

Cf. A224681, A224678, A224607.

Sequence in context: A348901 A363480 A193199 * A075986 A251657 A084765

Adjacent sequences: A224677 A224678 A224679 * A224681 A224682 A224683

Keyword

nonn

Author

Paul D. Hanna, Apr 14 2013

Status

approved