

A192821


3Ramanujan primes; the interval (x/2,x] has at least n 2Ramanujan primes for x >= a(n) but not for x = a(n)1.


6



41, 149, 227, 229, 233, 569, 571, 587, 593, 641, 643, 821, 937, 941, 1367, 1373, 1423, 1439, 1481, 1549, 1553, 2207, 2237, 2239, 2267, 2269, 2273, 2281, 2333, 2339, 2347, 2377, 2617, 2657, 3251, 3257, 3259, 3299, 3343, 3347, 3449, 3581, 3583, 3607, 3613
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OFFSET

1,1


COMMENTS

It is conjectured that primepi(a(n)) < 10*n for large n.  T. D. Noe, Aug 26 2011
The sequence is only conjectural without a proof of an upper bound on a(n) (like the bound A104272(n) < prime(3*n) proved by Laishram and used in computing Ramanujan primes).  Jonathan Sondow, Aug 26 2011
Subsequence of the 2Ramanujan primes A192820, by the minimality of a(n).  Jonathan Sondow, Aug 21 2012


LINKS

Table of n, a(n) for n=1..45.


CROSSREFS

Cf. A104272 (Ramanujan primes), A192820 (2Ramanujan primes), A192822, A192823, A192824.
Sequence in context: A146330 A146350 A050954 * A141957 A108016 A142630
Adjacent sequences: A192818 A192819 A192820 * A192822 A192823 A192824


KEYWORD

nonn


AUTHOR

T. D. Noe, Jul 11 2011


EXTENSIONS

Definition clarified by Jonathan Sondow, Aug 21 2012


STATUS

approved



