This site is supported by donations to The OEIS Foundation.

 Hints (Greetings from The On-Line Encyclopedia of Integer Sequences!)
 A074707 exp(Sum_{n>0} x^n/n^2) = Sum_{n>=0} a(n)*x^n/n!^2. 2
 1, 1, 3, 19, 214, 3846, 102206, 3795758, 188648664, 12125977944, 980768153832, 97599402813672, 11728820086206576, 1675575398007779568, 280777781273956353648, 54556438705747006028016, 12169284368165386948212096, 3088938134820388829982311808 (list; graph; refs; listen; history; text; internal format)
 OFFSET 0,3 REFERENCES R. L. Graham, D. E. Knuth and O. Patashnik, Concrete Mathematics, second edition, Addison Wesley, pp. 464-466. LINKS FORMULA a(n)=n!^2/n*sum(k=0, n-1, a(k)/k!^2/(n-k)). a(n)/n!^2 = exp(Pi^2/6)/n^2 + O(log(n)/n^3). - Benoit Cloitre, Jan 11 2003 PROG (PARI) a(n)=if(n<2, 1, (n-1)!^2+n!^2/n*sum(k=1, n-1, a(k)/k!^2/(n-k))) (PARI) {a(n)=n!^2*polcoeff(exp(sum(m=1, n, x^m/m^2)+x*O(x^n)), n)} CROSSREFS Cf. A193436, A217145. Sequence in context: A165356 A000275 A058165 * A230317 A135749 A005647 Adjacent sequences:  A074704 A074705 A074706 * A074708 A074709 A074710 KEYWORD nonn AUTHOR Vladeta Jovovic, Sep 04 2002 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 October 17 06:08 EDT 2019. Contains 328106 sequences. (Running on oeis4.)