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A162336 Primes p of the form p = r+(r+1)/2 (where r is a prime number). 5
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 (list; graph; refs; listen; history; text; internal format)
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

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Last modified April 23 01:31 EDT 2021. Contains 343198 sequences. (Running on oeis4.)