A241945 Indices n where both prime(n) + 2*prime(n+1) and 2*prime(n) + prime(n+1) are primes.

2, 3, 6, 17, 27, 30, 48, 53, 57, 68, 94, 137, 138, 143, 156, 157, 248, 259, 269, 289, 296, 316, 360, 369, 402, 425, 429, 430, 432, 446, 474, 500, 522, 580, 596, 631, 656, 760, 777, 810, 828, 875, 906, 951, 994, 1154, 1163, 1233, 1273, 1338, 1346, 1352, 1378, 1381, 1385, 1391, 1402, 1422, 1436, 1495, 1552, 1602

Offset

1,1

Links

Amiram Eldar and Zak Seidov, Table of n, a(n) for n = 1..10000

Example

n=2 is in the sequence because 3 + 2*5 = 13 and 5 + 2*3 = 11 are primes.
n=3 is in the sequence because 5 + 2*7 = 19 and 7 + 2*5 = 17 are primes.
n=6 is in the sequence because 17 + 2*13 = 43 and 13 + 2*17 = 47 are primes.

Prog

(PARI) isok(n) = my(p=prime(n), q=nextprime(p+1)); isprime(p+2*q) && isprime(2*p+q); \\ Michel Marcus, Jan 06 2019

Crossrefs

Cf. A094104 (primes of form 2*p + q), A094105 (primes of form p + 2*q).

Cf. A181848, A186169, A215684.

Sequence in context: A230146 A102980 A181185 * A018284 A204514 A338594

Adjacent sequences: A241942 A241943 A241944 * A241946 A241947 A241948

Keyword

nonn

Author

Zak Seidov, May 03 2014

Status

approved