A180606 - OEIS

%I #2 Mar 30 2012 18:37:22

%S 1,1,2,18,862,185582,165592644,599576207236,8764375895813558,

%T 516573425446007525398,122710727732550268600238492,

%U 117431929105754130321446873061820

%N G.f.: A(x) = exp( Sum_{n>=1} (2^n-1)^(n-1)*x^n/n ).

%e G.f.: A(x) = 1 + x + 2*x^2 + 18*x^3 + 862*x^4 + 185582*x^5 +...

%e log(A(x)) = x + 3*x^2/2 + 7^2*x^3/3 + 15^3*x^4/4 + 31^4*x^5/5 +...

%o (PARI) {a(n)=polcoeff(exp(sum(m=1,n,(2^m-1)^(m-1)*x^m/m)+x*O(x^n)),n)}

%Y Cf. A180602.

%K nonn

%O 0,3

%A _Paul D. Hanna_, Sep 26 2010