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 A083351 Numbers n such that 5*7^n + 2 is prime. 0
 0, 1, 4, 9, 12, 25, 132, 192, 459 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,3 COMMENTS Values corresponding to 9, 12, 25, 132, 192 and 459 (389 digits) have been certified prime with Primo. There are no other terms <= 4000. LINKS EXAMPLE 7, 37, 12007, 201768037, 69206436007, 6705343098319824504037 are 5*7^0 + 2, 5*7^1 + 2, 5*7^4 + 2, 5*7^9 + 2, 5*7^12 + 2, 5*7^25 + 2, respectively. 5*7^132 + 2 has 113 digits. PROG (PARI) for(n=0, 4000, if(isprime(5*7^n+2), print1(n, ", "))) CROSSREFS Sequence in context: A254520 A283105 A179808 * A055381 A287498 A174911 Adjacent sequences:  A083348 A083349 A083350 * A083352 A083353 A083354 KEYWORD nonn AUTHOR Rick L. Shepherd, Apr 26 2003 STATUS approved

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Last modified December 10 23:13 EST 2019. Contains 329909 sequences. (Running on oeis4.)