A192821 3-Ramanujan primes; the interval (x/2,x] has at least n 2-Ramanujan primes for x >= a(n) but not for x = a(n)-1.

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

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 2-Ramanujan 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 (2-Ramanujan primes), A192822, A192823, A192824.

Sequence in context: A146350 A050954 A337872 * 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