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A020901 Greatest k such that k-th prime < 3 times n-th prime. 10
3, 4, 6, 8, 11, 12, 15, 16, 19, 23, 24, 29, 30, 31, 34, 37, 40, 42, 46, 47, 47, 51, 53, 56, 61, 62, 63, 66, 66, 68, 75, 77, 80, 80, 86, 87, 91, 93, 95, 97, 99, 100, 105, 106, 107, 108, 115, 121, 123, 124, 125, 127, 128, 133, 136, 138, 139, 141, 145 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

LINKS

Harvey P. Dale, Table of n, a(n) for n = 1..1000

MATHEMATICA

Table[PrimePi[NextPrime[3Prime[n], -1]], {n, 60}] (* Harvey P. Dale, Feb 21 2014 *)

PROG

(PARI) a(n) = primepi(3*prime(n)) \\ Michel Marcus, Mar 22 2013

CROSSREFS

Cf. A020900, A020934-A020940.

Sequence in context: A080728 A047414 A109402 * A181714 A057057 A186154

Adjacent sequences:  A020898 A020899 A020900 * A020902 A020903 A020904

KEYWORD

nonn

AUTHOR

Clark Kimberling

STATUS

approved

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Last modified April 25 16:59 EDT 2019. Contains 322461 sequences. (Running on oeis4.)