A238204 Even numbers n such that the difference with the preceding prime is prime.

10, 16, 22, 26, 28, 34, 36, 40, 46, 50, 52, 56, 58, 64, 66, 70, 76, 78, 82, 86, 88, 92, 94, 96, 100, 106, 112, 116, 118, 120, 124, 126, 130, 134, 136, 142, 144, 146, 154, 156, 160, 162, 166, 170, 172, 176, 178, 184, 186, 188, 196, 202, 204, 206, 210, 214, 216

Offset: 1

Author

Franz Vrabec, Feb 20 2014

Keywords

• nonn

Examples

			28 is in the list because 23 is the greatest prime less than 28 and 28 - 23 = 5 is also prime.
		

Links

• Vincenzo Librandi, Table of n, a(n) for n = 1..1000

Programs

Maple

a:= proc(n) option remember; local k;
      for k from `if`(n=1, 4, a(n-1)+2) by 2
      while not isprime(k-prevprime(k)) do od; k
    end:
seq(a(n), n=1..60);  # Alois P. Heinz, Mar 03 2014

Mathematica

Select[Range[99] 2, PrimeQ[# - NextPrime[#, -1]] &] (* Giovanni Resta, Feb 22 2014 *)