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 A102787 Integer part of n#/((p-5)# 5#), where p=preceding prime to n. 0
 0, 0, 0, 3, 2, 4, 7, 10, 14, 0, 29, 1, 50, 58, 67, 1, 1, 119, 2, 158, 172, 2, 218, 2, 3, 326, 346, 367, 388, 410, 4, 554, 4, 634, 4, 749, 5, 5, 907, 5, 5, 1079, 6, 1228, 1267, 1306, 7, 7, 1687, 1732, 1778, 7, 1919, 8, 8, 8, 8, 2429, 9, 2594, 2650, 9 (list; graph; refs; listen; history; text; internal format)
 OFFSET 2,4 COMMENTS 0# = 1# = 2 by convention. LINKS FORMULA n# = product of primes <= n. 0#=1#=2. n#/((p-r)# r#) is analogous to the number of combinations of n things taken r at a time: C(n, r) = n!/((n-r)! r!) where factorial ! is replaced by primorial # and n is replaced with the prime preceding n. PROG (PARI) c(n, r) = { local(p); forprime(p=r, n, print1(floor(primorial(p)/primorial(p-r)/primorial(r)+.0)", ") ) } 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: A276944 A300501 A158441 * A014193 A128885 A215335 Adjacent sequences:  A102784 A102785 A102786 * A102788 A102789 A102790 KEYWORD easy,nonn AUTHOR Cino Hilliard, Feb 25 2005 STATUS approved

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Last modified June 1 03:14 EDT 2020. Contains 334758 sequences. (Running on oeis4.)