OFFSET
0,2
COMMENTS
A self-convolution of an integer sequence (A222081).
LINKS
Paul D. Hanna, Table of n, a(n) for n = 0..300
EXAMPLE
The terms satisfy:
1 = (1-x)^2 + 2*x*(1-3*x)^2 + 11*x^2*(1-5*x)^2 + 92*x^3*(1-7*x)^2 + 1013*x^4*(1-9*x)^2 + 13726*x^5*(1-11*x)^2 + 219919*x^6*(1-13*x)^2 +...
G.f.: A(x) = 1 + 2*x + 11*x^2 + 92*x^3 + 1013*x^4 + 13726*x^5 + 219919*x^6 + 4057048*x^7 + 84545129*x^8 +...
The square-root of g.f. A(x) is an integer series:
A(x)^(1/2) = 1 + x + 5*x^2 + 41*x^3 + 453*x^4 + 6205*x^5 + 100649*x^6 + 1878277*x^7 + 39534033*x^8 +...+ A222081(n)*x^n +...
PROG
(PARI) {a(n)=polcoeff(1-sum(m=0, n-1, a(m)*x^m*(1-(2*m+1)*x+x*O(x^n))^2), n)}
for(n=0, 25, print1(a(n), ", "))
CROSSREFS
KEYWORD
nonn
AUTHOR
Paul D. Hanna, Feb 07 2013
STATUS
approved