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A102790
Integer part of n#/(p-3)#, where p=preceding prime to n.
0
3, 15, 35, 11, 143, 17, 323, 23, 29, 899, 37, 41, 1763, 47, 53, 59, 3599, 67, 71, 5183, 79, 83, 89, 97, 101, 10403, 107, 11663, 113, 127, 131, 137, 19043, 149, 22499, 157, 163, 167, 173, 179, 32399, 191, 36863, 197, 39203, 211, 223, 227, 51983, 233, 239, 57599
OFFSET
2,1
COMMENTS
0# = 1# = 2 by convention.
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: A009261 A372735 A331249 * A317182 A236693 A317183
KEYWORD
easy,nonn
AUTHOR
Cino Hilliard, Feb 25 2005
STATUS
approved