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A071854
a(n) = (number of distinct prime factors in C(2n,n)) - pi(n).
1
1, 1, 0, 1, 0, 1, 0, 1, 1, 1, 1, 1, 0, 0, 1, 2, 1, 2, 1, 2, 2, 2, 0, 1, 1, 1, 1, 3, 3, 2, 1, 2, 3, 3, 3, 3, 2, 3, 2, 3, 2, 3, 2, 2, 3, 3, 2, 3, 3, 3, 3, 3, 3, 4, 3, 3, 3, 4, 3, 4, 3, 3, 3, 4, 4, 5, 5, 4, 4, 4, 3, 4, 3, 3, 4, 4, 5, 5, 4, 5, 5, 5, 4, 4, 4, 5, 5, 5, 4, 4, 5, 6, 5, 5, 5, 6, 5, 4, 5, 6, 5, 6, 5, 6, 6
OFFSET
1,16
FORMULA
a(n) = A067434(n) - A000720(n)
PROG
(PARI) for(n=1, 200, print1(omega(binomial(2*n, n))-sum(i=1, n, isprime(i)), ", "))
CROSSREFS
Sequence in context: A083870 A368779 A052299 * A183025 A072410 A342824
KEYWORD
nonn
AUTHOR
Benoit Cloitre, Jun 09 2002
STATUS
approved