OFFSET
0,3
FORMULA
a(n) == 1 (mod 6).
EXAMPLE
G.f.: A(x) = 1 + x + 13*x^2 + 127*x^3 + 21079*x^4 + 5748277*x^5 +...
such that
log(A(x)) = x + 5^2*x^2 + 7^3*x^3 + 17^4*x^4 + 31^5*x^5 + 65^6*x^6 + 127^7*x^7 +...+ (2^n + (-1)^n)^n*x^n/n +...
PROG
(PARI) {a(n)=polcoeff(exp(sum(k=1, n, (2^k+(-1)^k)^k*x^k/k)+x*O(x^n)), n)}
for(n=0, 20, print1(a(n), ", "))
CROSSREFS
KEYWORD
nonn
AUTHOR
Paul D. Hanna, Apr 25 2012
STATUS
approved