A032617 Numbers k such that k concatenated with k+2 is a prime.

1, 7, 9, 27, 37, 45, 49, 51, 55, 61, 69, 75, 105, 109, 115, 117, 121, 151, 159, 181, 187, 195, 201, 211, 217, 225, 247, 271, 277, 285, 289, 291, 301, 309, 319, 321, 331, 337, 339, 357, 361, 367, 381, 391, 399, 405, 417, 421, 427, 429, 435, 439

Offset

1,2

Links

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

Maple

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

Crossrefs

Cf. A032607.

Sequence in context: A125260 A192859 A104703 * A113124 A324986 A030404

Adjacent sequences: A032614 A032615 A032616 * A032618 A032619 A032620

Keyword

nonn,base

Author

Patrick De Geest, May 15 1998

Status

approved