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A185371
Product of two consecutive primes divided by the next prime and rounded down.
1
1, 2, 3, 5, 8, 11, 14, 15, 21, 24, 27, 35, 37, 38, 42, 51, 53, 57, 65, 65, 69, 73, 76, 85, 95, 97, 101, 103, 96, 109, 121, 129, 127, 137, 143, 145, 153, 157, 161, 171, 169, 179, 187, 191, 185, 188, 207, 221, 223, 223, 231, 229, 235, 245, 251, 261, 263, 267, 275
OFFSET
2,2
LINKS
FORMULA
a(n)=[p(n)*p(n+1)/p(n+2)], where p(n) is the n-th prime and [] is the floor function .
For n > 3, prime(n)/2 < a(n) < prime(n). prime(n) - a(n) << log(n)^2 under Cramer's conjecture. Weaker estimates follow from the Prime Number Theorem. - Charles R Greathouse IV, Jan 26 2012
EXAMPLE
[2*3/5]=1; [3*5/7]=2; [5*7/11]=3
MATHEMATICA
Table[Floor[Prime[n]*Prime[n + 1]/Prime[n + 2]], {n, 1, 50}] (* G. C. Greubel, Jun 28 2017 *)
PROG
(PARI) p=2; q=3; forprime(r=5, 1e3, print1(p*q\r", "); p=q; q=r) \\ Charles R Greathouse IV, Jan 26 2012
CROSSREFS
Sequence in context: A228855 A171048 A209292 * A071894 A301892 A271876
KEYWORD
nonn
AUTHOR
Tyler Carrico, Jan 26 2012
EXTENSIONS
a(14)-a(15) corrected, a(16)-a(59) from Charles R Greathouse IV, Jan 26 2012
STATUS
approved