The OEIS Foundation is supported by donations from users of the OEIS and by a grant from the Simons Foundation.

Thanks to everyone who made a donation during our annual appeal!
To see the list of donors, or make a donation, see the OEIS Foundation home page.

 Hints (Greetings from The On-Line Encyclopedia of Integer Sequences!)
 A155207 G.f.: A(x) = exp( Sum_{n>=1} 4^(n^2) * x^n/n ), a power series in x with integer coefficients. 6
 1, 4, 136, 87904, 1074100576, 225184288253824, 787061981348092400896, 45273238870711805132010916864, 42535296046210357883346895894694749696, 649556283428320264374891976653586736162144180224 (list; graph; refs; listen; history; text; internal format)
 OFFSET 0,2 COMMENTS More generally, for m integer, exp( Sum_{n>=1} m^(n^2) * x^n/n ) is a power series in x with integer coefficients. LINKS EXAMPLE G.f.: A(x) = 1 + 4*x + 136*x^2 + 87904*x^3 + 1074100576*x^4 +... log(A(x)) = 4*x + 4^4*x^2/2 + 4^9*x^3/3 + 4^16*x^4/4 + 4^25*x^5/5 +... PROG (PARI) {a(n)=polcoeff(exp(sum(m=1, n+1, 4^(m^2)*x^m/m)+x*O(x^n)), n)} CROSSREFS Cf. A155208, A155209, A155210, variants: A155200, A155203. Sequence in context: A012070 A001374 A229416 * A201388 A089666 A029850 Adjacent sequences:  A155204 A155205 A155206 * A155208 A155209 A155210 KEYWORD nonn AUTHOR Paul D. Hanna, Feb 04 2009 STATUS approved

Lookup | Welcome | Wiki | Register | Music | Plot 2 | Demos | Index | Browse | More | WebCam
Contribute new seq. or comment | Format | Style Sheet | Transforms | Superseeker | Recent
The OEIS Community | Maintained by The OEIS Foundation Inc.

Last modified January 17 09:49 EST 2020. Contains 330949 sequences. (Running on oeis4.)