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A102791 Integer part of n#/(p-5)#, where p=preceding prime to n. 0
15, 105, 77, 143, 221, 323, 437, 29, 899, 37, 1517, 1763, 2021, 53, 59, 3599, 67, 4757, 5183, 79, 6557, 89, 97, 9797, 10403, 11021, 11663, 12317, 127, 16637, 137, 19043, 149, 22499, 157, 163, 27221, 173, 179, 32399, 191, 36863, 38021, 39203, 211, 223 (list; graph; refs; listen; history; text; internal format)
OFFSET

5,1

COMMENTS

0# = 1# = 2 by convention.

LINKS

Table of n, a(n) for n=5..50.

FORMULA

n# = product of primes <= n. 0#=1#=2. n#/(p-r)# is analogous to the number of permutations of n things taken r at a time: P(n, r) = n!/(n-r)! where factorial ! is replaced by primorial # and n is replaced with the preceding prime to n.

PROG

(PARI) perm(n, r) = { local(p); forprime(p=r, n, print1(floor(primorial(p)/primorial(p-r))", ") ) } primorial(n) = \ The product of primes <= n using the pari primelimit. { local(p1, x); if(n==0||n==1, return(2)); p1=1; forprime(x=2, n, p1*=x); return(p1) }

CROSSREFS

Sequence in context: A227331 A223441 A300295 * A160892 A061550 A174385

Adjacent sequences:  A102788 A102789 A102790 * A102792 A102793 A102794

KEYWORD

easy,nonn

AUTHOR

Cino Hilliard, Feb 25 2005

STATUS

approved

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Last modified May 28 04:36 EDT 2020. Contains 334671 sequences. (Running on oeis4.)