login
The OEIS Foundation is supported by donations from users of the OEIS and by a grant from the Simons Foundation.

 

Logo


Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
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 (list; graph; refs; listen; history; text; internal format)
OFFSET

2,1

COMMENTS

0# = 1# = 2 by convention.

LINKS

Table of n, a(n) for n=2..53.

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: A324303 A009261 A331249 * A317182 A236693 A317183

Adjacent sequences:  A102787 A102788 A102789 * A102791 A102792 A102793

KEYWORD

easy,nonn

AUTHOR

Cino Hilliard, Feb 25 2005

STATUS

approved

Lookup | Welcome | Wiki | Register | Music | Plot 2 | Demos | Index | Browse | More | WebCam
Contribute new seq. or comment | Format | Style Sheet | Transforms | Superseeker | Recent
The OEIS Community | Maintained by The OEIS Foundation Inc.

License Agreements, Terms of Use, Privacy Policy. .

Last modified July 4 16:24 EDT 2020. Contains 335448 sequences. (Running on oeis4.)