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A023986 Sum of exponents of primes in C(4n,2n)/C(2n,n). 1
1, 1, 2, 3, 1, 2, 5, 3, 5, 6, 4, 6, 6, 3, 4, 6, 5, 4, 6, 5, 8, 10, 7, 9, 9, 7, 9, 8, 7, 10, 12, 10, 9, 13, 11, 13, 16, 12, 13, 14, 9, 11, 12, 12, 13, 12, 12, 13, 15, 11, 13, 16, 13, 15, 17, 16, 19, 19, 16, 15, 17, 18, 15, 18, 17, 19, 19, 13, 17, 19, 17, 18, 18, 15, 19, 21, 18, 17, 20, 19, 19, 22, 19, 22 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,3

LINKS

Charles R Greathouse IV, Table of n, a(n) for n = 1..10000

PROG

(PARI) a(n) = my(v = binomial(4*n, 2*n)/binomial(2*n, n)); bigomega(numerator(v)) - bigomega(denominator(v)); \\ Michel Marcus, Sep 30 2013

(PARI) vp(n, p)=my(s); while(n\=p, s+=n); s

a(n)=my(s); forprime(p=2, 4*n, s+=vp(4*n, p)-3*vp(2*n, p)+2*vp(n, p)); s \\ Charles R Greathouse IV, Sep 30 2013

CROSSREFS

Sequence in context: A190257 A050981 A053452 * A306732 A109202 A245559

Adjacent sequences:  A023983 A023984 A023985 * A023987 A023988 A023989

KEYWORD

nonn

AUTHOR

Clark Kimberling

STATUS

approved

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Last modified September 21 07:08 EDT 2019. Contains 327253 sequences. (Running on oeis4.)