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%I #15 Apr 19 2014 03:59:21
%S 0,0,1,1,2,3,3,3,4,4,4,5,5,5,6,6,7,8,8,9,9,9,9,9,9,9,9,10,11,11,11,11,
%T 12,13,13,13,13,13,13,14,14,15,15,15,16,16,16,17,17,17,17,17,17,19,18,
%U 18,18,18,19,19,20,20,20,20,21,22,22,23,22,22,22,23,23,23,24,24,25,25
%N Number of distinct primes dividing n-th Catalan number.
%H Enrique Pérez Herrero, <a href="/A080405/b080405.txt">Table of n, a(n) for n = 0..3000</a>
%F a(n) = A001221(A000108(n)).
%e a(5) = 3, as C(5) = 42 factors as 2*3*7 (3 distinct prime factors).
%t PrimeNu[CatalanNumber[Range[0,80]]] (* _Harvey P. Dale_, Mar 27 2013 *)
%o (PARI) C(n)=binomial(2*n,n)/(n+1);
%o for(n=1,100,print1(matsize(factor(C(n-1)))[1],", ")); \\ _Joerg Arndt_, Apr 19 2014
%Y Cf. A001221, A000108.
%Y Cf. A081399.
%K nonn
%O 0,5
%A _Labos Elemer_, Mar 19 2003
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