

A234695


Primes p with prime(p)  p + 1 also prime.


38



2, 3, 5, 7, 13, 17, 23, 31, 41, 43, 61, 71, 83, 89, 103, 109, 139, 151, 173, 181, 199, 211, 223, 241, 271, 277, 281, 293, 307, 311, 317, 337, 349, 353, 367, 463, 499, 541, 563, 571, 601, 661, 673, 709, 719, 743, 751, 757, 811, 823, 827, 883, 907, 911, 953
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OFFSET

1,1


COMMENTS

By the conjecture in A234694, this sequence should have infinitely many terms.


LINKS

ZhiWei Sun, Table of n, a(n) for n = 1..10000
Z.W. Sun, Problems on combinatorial properties of primes, arXiv:1402.6641, 2014


FORMULA

a(n) = prime(A234852(n)).  M. F. Hasler, Dec 31 2013


EXAMPLE

a(1) = 2 since prime(2)  1 = 2 is prime.
a(2) = 3 since prime(3)  2 = 3 is prime.
a(3) = 5 since prime(5)  4 = 7 is prime.
a(4) = 7 since prime(7)  6 = 11 is prime.


MATHEMATICA

n=0; Do[If[PrimeQ[Prime[Prime[k]]Prime[k]+1], n=n+1; Print[n, " ", Prime[k]]], {k, 1, 1000}]


PROG

(PARI) forprime(p=1, 999, isprime(prime(p)p+1)&&print1(p", ")) \\  M. F. Hasler, Dec 31 2013


CROSSREFS

Cf. A000040, A014692, A234694.
Sequence in context: A089438 A155777 A262839 * A067905 A042993 A308711
Adjacent sequences: A234692 A234693 A234694 * A234696 A234697 A234698


KEYWORD

nonn


AUTHOR

ZhiWei Sun, Dec 29 2013


STATUS

approved



