A162336 Primes p of the form p = r+(r+1)/2 (where r is a prime number).

5, 11, 17, 29, 47, 71, 89, 101, 107, 191, 197, 227, 251, 269, 317, 359, 461, 467, 521, 569, 647, 659, 701, 719, 821, 857, 881, 911, 929, 947, 971, 1091, 1109, 1181, 1217, 1259, 1289, 1361, 1367, 1451, 1487, 1559, 1637, 1847, 1889, 1979, 2099, 2141, 2207

Offset

1,1

Comments

Or primes of the form Sum_{x=1..n-th prime} (1-(-1)^x*x). - Juri-Stepan Gerasimov, Jul 14 2009

Primes p such that (2*p-1)/3 is prime. - J. M. Bergot, Aug 19 2020

Links

Robert Israel, Table of n, a(n) for n = 1..10000

Example

3+2=5, 7+4=11, 11+6=17, 19+10=29, 31+16=47, 47+24=71,.. r:3,7,11,19,31,47,59,67,71,127,131,151,167,179,211,239,307,311, ..A158709.

Maple

filter:= p -> isprime(p) and isprime((2*p-1)/3):
select(filter, [seq(i, i=5..10000, 6)]); # Robert Israel, Aug 19 2020

Mathematica

lst={}; Do[r=Prime[n]; p=r+(r+1)/2; If[PrimeQ[p], AppendTo[lst, p]], {n, 6!}]; lst
Select[#+(#+1)/2&/@Prime[Range[300]], PrimeQ] (* Harvey P. Dale, Apr 30 2015 *)

Crossrefs

Cf. A158709.

Sequence in context: A184247 A046135 A331946 * A234346 A074267 A268518

Adjacent sequences: A162333 A162334 A162335 * A162337 A162338 A162339

Keyword

nonn

Author

Vladimir Joseph Stephan Orlovsky, Jul 01 2009

Extensions

Edited by N. J. A. Sloane, Jul 18 2009

Status

approved