A339868 Primes p such that p + A023896(p-1) and p + A023896(p+1) are prime.

2, 7, 29, 61, 83, 109, 293, 311, 449, 709, 773, 997, 1021, 1031, 1103, 1231, 1297, 1301, 1381, 1487, 1523, 1553, 1559, 1709, 2089, 2161, 2221, 2297, 2339, 2377, 2521, 2663, 2677, 2687, 2711, 2927, 3037, 3163, 3167, 3221, 3407, 3533, 4091, 4259, 4729, 5009, 5189, 5309, 5581, 6691, 6899, 7001, 7297

Offset

1,1

Links

Robert Israel, Table of n, a(n) for n = 1..10000

Example

a(3) = 29 is a term because 29, 29 + A023896(28) = 197 and 29 + A023896(30) = 149 are prime.

Maple

A023896:= n -> n*numtheory:-phi(n)/2:
A023896(1):= 1:
select(t -> isprime(t+A023896(t-1)) and isprime(t+A023896(t+1)),
[seq(ithprime(i), i=1..1000)]);

Crossrefs

Cf. A023896.

Sequence in context: A162172 A274682 A359633 * A181758 A285790 A083016

Adjacent sequences: A339865 A339866 A339867 * A339869 A339870 A339871

Keyword

nonn

Author

J. M. Bergot and Robert Israel, Dec 20 2020

Status

approved