A103534 Concatenations of pairs of primes that differ by 1000.

131013, 191019, 311031, 611061, 971097, 1031103, 1091109, 1511151, 1631163, 1811181, 1931193, 2231223, 2291229, 2771277, 2831283, 3071307, 3671367, 3731373, 4091409, 4331433, 4391439, 4871487, 4991499, 5231523, 5711571

Offset: 1

Author

Jonathan Vos Post, Mar 22 2005

Keywords

• base
• easy
• nonn

Comments

All terms are multiples of 3.

Examples

			1811181 is in this sequence because 181 is prime, 181+1000 = 1181 is prime and those two primes are concatenated.
		

Crossrefs

Cf. A100750, A103195, A103206, A104718, A104719, A103523.

Programs

Mathematica

10001#+1000&/@Select[Prime[Range[150]],PrimeQ[#+1000]&] (* Harvey P. Dale, Sep 01 2017 *)

Formula

a(n) = Concatenate(P, P+1000) iff P prime and P+1000 prime.