A245742 - OEIS

A245742

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

%I #24 Sep 08 2022 08:46:09

%S 43,61,263,461,563,601,613,641,653,683,821,1063,1283,1361,1423,1481,

%T 1601,1613,1621,1663,1823,1871,2063,2081,2111,2381,2843,3061,3163,

%U 3343,3461,3463,3631,3881,4003,4561,4583,4643,4651,5563,5641,5651,5653,5783,5813

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

%C The least significant digit of a(n) is either 1 or 3. - _Colin Barker_, Aug 03 2014

%C The largest digit of a(n) is 2, 4, 6 or 8. - _Colin Barker_, Aug 04 2014

%H Jens Kruse Andersen, <a href="/A245742/b245742.txt">Table of n, a(n) for n = 1..10000</a>

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

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

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

%o (Magma) [p: p in PrimesUpTo(7000) | IsPrime(p+d) where d is Max(Intseq(p))]; // _Bruno Berselli_, Jul 31 2014

%Y Cf. A245743, A245744, A245745.

%K nonn,base

%O 1,1

%A _Colin Barker_, Jul 31 2014