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A270563 Integers n such that A086167(n) and A086168(n) are both prime. 0
1, 15, 45, 105, 135, 231, 807 (list; graph; refs; listen; history; text; internal format)



A013916 lists numbers n such that the sum of the first n primes is prime. With similar motivation, twin prime pairs generate prime pairs in this sequence. Note that 2*n also gives the difference between members of prime pair that is generated by sum of first n twin prime pairs.

First differences of this sequence are 14, 30, 60, 30, 96, 576, ...


Table of n, a(n) for n=1..7.


15 is a term since A086167(15) = 1297 and A086168(15) = 1297 + 15*2 = 1327. 1297 and 1327 are both prime.


(PARI) t(n, p=3) = {while( p+2 < (p=nextprime( p+1 )) || n-->0, ); p-2}

s1(n) = sum(k=1, n, t(k));

s2(n) = sum(k=1, n, t(k)+2);

for(n=1, 1e3, if(ispseudoprime(s1(n)) && ispseudoprime(s2(n)), print1(n, ", ")));


Cf. A086167, A086168.

Sequence in context: A014634 A303857 A278337 * A126228 A072251 A002756

Adjacent sequences:  A270560 A270561 A270562 * A270564 A270565 A270566




Altug Alkan, Mar 19 2016



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Last modified December 5 17:42 EST 2019. Contains 329768 sequences. (Running on oeis4.)