A245742 Primes p such that p + d is also prime, where d is the largest digit of p.

43, 61, 263, 461, 563, 601, 613, 641, 653, 683, 821, 1063, 1283, 1361, 1423, 1481, 1601, 1613, 1621, 1663, 1823, 1871, 2063, 2081, 2111, 2381, 2843, 3061, 3163, 3343, 3461, 3463, 3631, 3881, 4003, 4561, 4583, 4643, 4651, 5563, 5641, 5651, 5653, 5783, 5813

Offset: 1

Author

Colin Barker, Jul 31 2014

Keywords

• nonn
• base

Comments

The least significant digit of a(n) is either 1 or 3. - Colin Barker, Aug 03 2014

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

Examples

			263 is in the sequence because 263 + 6 = 269, which is prime.
		

Links

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

Crossrefs

Cf. A245743, A245744, A245745.

Programs

Magma

[p: p in PrimesUpTo(7000) | IsPrime(p+d) where d is Max(Intseq(p))]; // Bruno Berselli, Jul 31 2014

Maple

select(p -> isprime(p) and isprime(p + max(convert(p,base,10))), [$1..1000]); # Robert Israel, Aug 03 2014

PARI

select(p->isprime(p+vecsort(digits(p),,4)[1]), primes(2000))