A168529 Primes n that are concatenation of two 3-digit primes p

101107, 101113, 101149, 101173, 101197, 101281, 101293, 101347, 101359, 101383, 101419, 101449, 101467, 101503, 101599, 101641, 101653, 101701, 101719, 101797, 101839, 101863, 101929, 101977, 103307, 103349, 103409, 103421, 103457, 103577

Offset: 1

Author

Zak Seidov, Nov 28 2009

Keywords

• base
• fini
• full
• nonn

Comments

Or, primes of the form 10^3*p+q, p,q primes, 100

There are exactly 1407 such primes from 101107 to 971977.

Links

• Andrew Howroyd, Table of n, a(n) for n = 1..1407 (complete sequence)

Crossrefs

Subsequence of A105184.

Programs

Mathematica

p3=Select[Range[100,999],PrimeQ];Le=Length@p3;Reap[Do[p=10^3*p3[[i]];Do[If[PrimeQ[n=p+p3[[k]]],Sow[n]],{k,i+1,Le}],{i,Le-1}]][[2,1]];

PARI

concat(apply(p->select(n->isprime(n) && isprime(n%1000),[1000*p+p+1..1000*p+997]), select(isprime,[101..996]))) \\ Andrew Howroyd, Feb 22 2018

Extensions

Terms a(25) and beyond in b-file corrected by Andrew Howroyd, Feb 22 2018

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