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A032629

Primes that are concatenations of k with k + 6.

17, 1117, 1319, 1723, 2531, 3137, 3541, 4349, 6571, 7177, 8389, 95101, 97103, 101107, 125131, 127133, 137143, 151157, 155161, 157163, 161167, 163169, 167173, 187193, 197203, 203209, 205211, 211217, 217223, 221227, 223229, 227233, 233239, 235241, 245251, 251257, 257263, 263269, 265271, 271277

(list; graph; refs; listen; history; text; internal format)

OFFSET

1,1

LINKS

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

MAPLE

tcat:= proc(a, b) a*10^(1+ilog10(b))+b end proc:

select(isprime, [seq(tcat(i, i+6), i=1..1000, 2)]); # Robert Israel, Nov 24 2025

MATHEMATICA

Select[Map[(# - 6)*10^IntegerLength[#] + # &, Range[7, 300, 2]], PrimeQ] (* Paolo Xausa, Nov 25 2025 *)

CROSSREFS

Cf. A032611, A032621.