This site is supported by donations to The OEIS Foundation.

 Hints (Greetings from The On-Line Encyclopedia of Integer Sequences!)
 A211611 Sum_{k=1..n-1} C(k)^n, where C(k) is a Catalan number. 3
 1, 9, 642, 540982, 5496576970, 698491214560174, 1147342896257677900291, 25005346993500437111980892595, 7381619397278667883874693730628586499, 30009934325456999669083059570156145437948880627, 1703283943023520710008632777768663744247664926649672215939 (list; graph; refs; listen; history; text; internal format)
 OFFSET 2,2 COMMENTS The C(k) are the Catalan numbers, C(k) = A000108(k) = (2k)!/k!/(k+1)! = C(2*k,k)/(k+1). p divides a(p) for prime p of the form p = 6k + 1. LINKS Eric Weisstein's World of Mathematics, Catalan Number FORMULA a(n) = Sum[ (Binomial[2 k, k]/(k + 1))^n, {k, 1, n - 1}]. a(n) ~ exp(3/8) * 4^(n^2-n) / (Pi^(n/2) * n^(3*n/2)). - Vaclav Kotesovec, Mar 03 2014 MATHEMATICA Table[ Sum[ (Binomial[2 k, k]/(k + 1))^n, {k, 1, n - 1}], {n, 2, 13}] CROSSREFS Cf. A000108, A211610, A238717. Sequence in context: A158881 A188394 A157597 * A280904 A210053 A128795 Adjacent sequences:  A211608 A211609 A211610 * A211612 A211613 A211614 KEYWORD nonn AUTHOR Alexander Adamchuk, Apr 17 2012 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 | More pages
The OEIS Community | Maintained by The OEIS Foundation Inc.