A032628 Primes that are concatenations of n with n + 5.

1217, 1621, 1823, 2833, 4651, 6469, 7681, 7883, 8287, 8893, 102107, 126131, 132137, 138143, 148153, 154159, 178183, 184189, 186191, 196201, 208213, 214219, 226231, 228233, 234239, 246251, 264269, 282287, 288293, 298303

Offset: 1

Author

Patrick De Geest, May 15 1998

Keywords

• nonn
• base

Links

• Harvey P. Dale, Table of n, a(n) for n = 1..600

Crossrefs

Cf. A032610, A032620.

Programs

Mathematica

concatQ[n_]:=Module[{idn=IntegerDigits[n],len},len=Length[idn];EvenQ[ len]&&FromDigits[Take[idn,-len/2]]-FromDigits[Take[idn,len/2]]==5]; Select[Prime[Range[30000]],concatQ] (* Harvey P. Dale, Jul 30 2015 *)

Extensions

Edited by Charles R Greathouse IV, Apr 28 2010