A245744 Primes p such that p + d is also prime, where d is the smallest nonzero digit of p.

29, 67, 89, 227, 239, 269, 457, 487, 499, 607, 677, 827, 2027, 2087, 2237, 2267, 2309, 2339, 2549, 2657, 2687, 2729, 2789, 2969, 2999, 3257, 3299, 3329, 3527, 3929, 4229, 4259, 4447, 4789, 4969, 4999, 5279, 5479, 5647, 6067, 6269, 6299, 6469, 6547, 6827

Offset: 1

Author

Colin Barker, Jul 31 2014

Keywords

• nonn
• base

Comments

The least significant digit of a(n) is either 7 or 9. - Colin Barker, Aug 03 2014

The smallest nonzero digit of a(n) is 2, 4, 6 or 8. - Colin Barker, Aug 04 2014

Examples

			607 is in the sequence because 607 + 6 = 613, which is prime.
		

Links

• Jens Kruse Andersen, Table of n, a(n) for n = 1..10000

Crossrefs

Cf. A245742, A245743, A245745.

Programs

Magma

[p: p in PrimesUpTo(7000) | IsPrime(p+d) where d is [i: i in Set(Intseq(p)) | not IsZero(i)][1]]; // Bruno Berselli, Jul 31 2014

PARI

select(p->v=vecsort(digits(p),,8); isprime(p+v[1+!v[1]]), primes(2000))