login
This site is supported by donations to The OEIS Foundation.

 

Logo


Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A023819 Sum of exponents in prime-power factorization of C(3n,n). 2
1, 2, 4, 4, 4, 6, 8, 6, 7, 8, 11, 11, 11, 11, 12, 10, 12, 11, 15, 13, 13, 18, 18, 17, 16, 17, 19, 17, 18, 19, 22, 18, 18, 20, 21, 19, 21, 22, 23, 22, 21, 23, 28, 27, 27, 28, 30, 27, 28, 26, 28, 29, 28, 31, 32, 29, 31, 31, 35, 32, 33, 35, 34, 31, 30, 31, 34, 31, 32, 35, 36, 33, 34, 35, 38, 37, 36, 36 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

COMMENTS

Equivalently, sum of exponents of primes in multinomial coefficient M(3n; n,n,n)/C(2n,n).

LINKS

Ivan Neretin, Table of n, a(n) for n = 1..10000

MAPLE

with(numtheory):(combinat):a:=proc(n) if n=0 then 0 else bigomega(binomial(3*n, n)) fi end: seq(a(n), n=1..78); # Zerinvary Lajos, Apr 11 2008

MATHEMATICA

Table[Total[FactorInteger[Binomial[3 n, n]][[All, 2]]], {n, 78}] (* Ivan Neretin, Nov 02 2017 *)

CROSSREFS

Sequence in context: A033825 A235790 A023988 * A201629 A033827 A008217

Adjacent sequences:  A023816 A023817 A023818 * A023820 A023821 A023822

KEYWORD

nonn

AUTHOR

Clark Kimberling

EXTENSIONS

Edited by N. J. A. Sloane at the suggestion of R. J. Mathar, May 31 2008

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.

License Agreements, Terms of Use, Privacy Policy. .

Last modified September 21 22:12 EDT 2019. Contains 327284 sequences. (Running on oeis4.)