|
Search: id:A102792
|
|
|
| A102792 |
|
Integer part of n#/(p-7)#, where p=preceding prime to n. |
|
+0
1
|
|
| 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; listen)
|
|
|
OFFSET
|
7,1
|
|
|
COMMENT
|
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.
|
|
PROGRAM
|
(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: A147576 A145752 A113480 this_sequence A013594 A160340 A136418
Adjacent sequences: A102789 A102790 A102791 this_sequence A102793 A102794 A102795
|
|
KEYWORD
|
easy,nonn
|
|
AUTHOR
|
Cino Hilliard (hillcino368(AT)gmail.com), Feb 25 2005
|
|
|
Search completed in 0.002 seconds
|
