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 A241945 Indices n where both prime(n) + 2*prime(n+1) and 2*prime(n) + prime(n+1) are primes. 4
 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 (list; graph; refs; listen; history; text; internal format)
 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

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Last modified April 17 13:58 EDT 2024. Contains 371764 sequences. (Running on oeis4.)