

A129488


Smallest odd prime dividing binomial(2n,n).


4



3, 5, 5, 3, 3, 3, 3, 5, 11, 3, 7, 5, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 7, 5, 3, 7, 7, 3, 3, 3, 3, 7, 7, 3, 5, 5, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 5, 5, 3, 5, 5, 3, 3, 3, 3, 5, 5, 3, 5, 5, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3
(list;
graph;
refs;
listen;
history;
text;
internal format)



OFFSET

2,1


COMMENTS

The Erdős paper calls this function g(n) and states that it not known whether it is bounded. Currently, g(3160)=13 is the greatest known value of g. See A129489.


LINKS



MATHEMATICA

Table[Transpose[FactorInteger[Binomial[2n, n]]][[1, 2]], {n, 2, 150}]


PROG

(PARI) a(n)=my(k); forprime(p=3, default(primelimit), k=1; while((k*=p)<=2*n, if(n/kn\k>1/2, return(p)))) \\ Charles R Greathouse IV, Dec 19 2011


CROSSREFS



KEYWORD

nonn


AUTHOR



STATUS

approved



