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A102792 Integer part of n#/(p-7)#, where p=preceding prime to n. 0
105, 385, 1001, 2431, 4199, 7429, 667, 899, 1147, 1517, 65231, 82861, 2491, 3127, 3599, 4087, 4757, 347261, 5767, 6557, 7387, 97, 9797, 1009091, 1113121, 1201289, 1317919, 127, 16637, 17947, 19043, 149, 22499, 23707, 25591, 27221, 28891, 30967 (list; graph; refs; listen; history; text; internal format)
OFFSET

7,1

COMMENTS

0# = 1# = 2 by convention.

LINKS

Table of n, a(n) for n=7..44.

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: A195266 A113480 A190577 * A013594 A160340 A136418

Adjacent sequences:  A102789 A102790 A102791 * A102793 A102794 A102795

KEYWORD

easy,nonn

AUTHOR

Cino Hilliard, Feb 25 2005

STATUS

approved

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Last modified March 29 17:23 EDT 2020. Contains 333116 sequences. (Running on oeis4.)