A032618 Numbers k such that k concatenated with k+3 is a prime.

4, 8, 10, 16, 44, 46, 56, 58, 68, 74, 86, 94, 98, 100, 104, 106, 136, 140, 148, 154, 158, 160, 166, 176, 184, 194, 206, 230, 244, 250, 254, 260, 266, 268, 274, 286, 296, 308, 310, 328, 338, 344, 346, 370, 380, 388, 410, 416, 430, 434, 436, 440, 448, 460

Offset: 1

Author

Patrick De Geest, May 15 1998

Keywords

• nonn
• base

Links

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

Crossrefs

Cf. A032608.

Programs

Maple

filter:= n -> isprime(n*(10^(1+ilog10(n+3))+1)+3):
select(filter, [seq(i,i=4..1000,2)]); # Robert Israel, Nov 14 2019

Mathematica

Select[Range[500],PrimeQ[FromDigits[Join[IntegerDigits[#], IntegerDigits[ #+3]]]]&] (* Harvey P. Dale, Jul 19 2011 *)