This site is supported by donations to The OEIS Foundation.

Annual Appeal: Please make a donation (tax deductible in USA) to keep the OEIS running. Over 4500 articles have referenced us, often saying "we would not have discovered this result without the OEIS".

 Hints (Greetings from The On-Line Encyclopedia of Integer Sequences!)
 A121612 Numbers n such that bigomega of n-th Catalan number divides n. 0
 2, 3, 4, 8, 10, 12, 16, 20, 22, 117, 408, 432, 444, 492, 504, 508, 1555, 1560, 1605, 1675, 1790, 5832, 5940, 5976, 6048, 6078, 6102, 6108, 6132, 6138, 21175, 21266, 21280, 21301, 21434, 21462, 21469, 21616, 21623, 21749, 21770, 21784 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,1 COMMENTS The number of prime divisors of n-th Catalan number (counted with multiplicity) divides n. LINKS FORMULA {n such that A081399(n)|n} = {n such that A001222[A000108(n)]|n}. EXAMPLE a(1) = 2 because bigomega(Catalan(2)) = bigomega(2) = 1 and 1 | 2. MATHEMATICA fQ[n_] := Mod[n, Plus @@ (Last@# & /@ FactorInteger[ Binomial[2n, n]/(n + 1)])] == 0; s = {}; Do[ If[fQ@n, Print@n; AppendTo[s, n]], {n, 2, 35500}] (* Robert G. Wilson v, Sep 11 2006 *) CROSSREFS Cf. A000108, A001222, A081399. Sequence in context: A073465 A174816 A161494 * A061193 A180941 A190896 Adjacent sequences:  A121609 A121610 A121611 * A121613 A121614 A121615 KEYWORD easy,nonn AUTHOR Jonathan Vos Post, Sep 08 2006 EXTENSIONS Corrected and extended (a(10)-a(42)) by Robert G. Wilson v, Sep 11 2006 STATUS approved

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

Content is available under The OEIS End-User License Agreement .