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 A155201 G.f.: A(x) = exp( Sum_{n>=1} (2^n + 1)^n * x^n/n ), a power series in x with integer coefficients. 8
 1, 3, 17, 285, 21747, 7894143, 12593691755, 84961748935779, 2379148487805445513, 273416748863491468927893, 128009274688933686165252807225, 242979449433397149030644307317592609, 1863847996727745781866688849374488247858333, 57652096246331953203644653244501049018464175026133 (list; graph; refs; listen; history; text; internal format)
 OFFSET 0,2 COMMENTS More generally, it appears that for m integer, exp( Sum_{n>=1} (m^n + y)^n * x^n/n ) is a power series in x and y with integer coefficients. LINKS FORMULA Equals row sums of triangle A155810. a(n) = (1/n)*Sum_{k=1..n} (2^k + 1)^k * a(n-k) for n>0, with a(0)=1. a(n) = B_n( 0!*(2^1+1)^1, 1!*(2^2+1)^2, 2!*(2^3+1)^3, ..., (n-1)!*(2^n+1)^n ) / n!, where B_n() is the n-th complete Bell polynomial. - Max Alekseyev, Oct 10 2014 EXAMPLE G.f.: A(x) = 1 + 3*x + 17*x^2 + 285*x^3 + 21747*x^4 + 7894143*x^5 +... log(A(x)) = 3*x + 5^2*x^2/2 + 9^3*x^3/3 + 17^4*x^4/4 + 33^5*x^5/5 +... PROG (PARI) {a(n)=polcoeff(exp(sum(m=1, n+1, (2^m+1)^m*x^m/m)+x*O(x^n)), n)} CROSSREFS Cf. A155200, A155202, A155810 (triangle), variants: A155204, A155208. Sequence in context: A009495 A153487 A267658 * A062622 A271609 A290806 Adjacent sequences:  A155198 A155199 A155200 * A155202 A155203 A155204 KEYWORD nonn AUTHOR Paul D. Hanna, Feb 04 2009 STATUS approved

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