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A075706 Safe primes (A005385) (p and (p-1)/2 are primes) such that 8*p+1 (A023228) is also prime. 0
5, 11, 107, 179, 347, 479, 1187, 1307, 1367, 1487, 1619, 2027, 2207, 2447, 2999, 3119, 3467, 4007, 4079, 4139, 4799, 5087, 5807, 5927, 5939, 6827, 7079, 7247, 8699, 9587, 9839, 10607, 12107, 12539, 12659, 14207, 15299, 16139, 16187, 17027 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

LINKS

Table of n, a(n) for n=1..40.

EXAMPLE

11 is a prime, so is (11-1)/2=5 and also 8*11+1=89; 107 is a prime, (107-1)/2=53 and 8*107+1=857, ...

MAPLE

ts_sg8_var_pras := proc(nmax) local i, tren, atek; tren := 0: for i from 1 to nmax do atek := numtheory[safeprime](i): if (atek > tren) then if (isprime(atek)='true' and isprime(6*atek+1)='true') then tren := atek: fi; fi; od; end: seq(ts_sg8_var_pras(i), i=1..3000);

PROG

(PARI) forprime(p=3, 20000, if(isprime((p-1)/2), if(isprime(8*p+1), print1(p", "))))

CROSSREFS

Cf. A005384, A005385, A059455, A023228.

Sequence in context: A056111 A090160 A062652 * A236509 A057178 A056265

Adjacent sequences:  A075703 A075704 A075705 * A075707 A075708 A075709

KEYWORD

nonn

AUTHOR

Jani Melik, Oct 02 2002

EXTENSIONS

More terms from Ralf Stephan, Mar 19 2003

STATUS

approved

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Last modified February 22 15:52 EST 2019. Contains 320399 sequences. (Running on oeis4.)