A245743 - OEIS

%I #18 Sep 08 2022 08:46:09

%S 41,163,181,263,401,443,463,487,563,613,653,1021,1381,1433,1613,1663,

%T 1831,2141,2243,2281,2441,2663,2851,2887,3041,3463,3613,3623,3643,

%U 4133,4363,4463,4603,4643,4663,4801,5281,5563,5581,5653,5821,5851,5857,6043,6053

%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, 3 or 7. - _Colin Barker_, Aug 03 2014

%C The largest digit of a(n) is 2, 4, 6 or 8. - _Robert Israel_, Aug 03 2014

%H Jens Kruse Andersen, <a href="/A245743/b245743.txt">Table of n, a(n) for n = 1..10000</a>

%e 263 is in the sequence because 263 - 6 = 257, which is prime.

%p filter:= n -> isprime(n) and isprime(n - max(convert(n,base,10))):

%p select(filter, [$1..10^5]); # _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. A245742, A245744, A245745.

%K nonn,base

%O 1,1

%A _Colin Barker_, Jul 31 2014