

A168529


Primes n that are concatenation of two 3digit primes p<q.


2



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
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OFFSET

1,1


COMMENTS

Or, primes of the form 10^3*p+q, p,q primes, 100<p<q<998.
There are exactly 1407 such primes from 101107 to 971977.


LINKS



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, Le1}]][[2, 1]];


PROG

(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


CROSSREFS



KEYWORD

base,fini,full,nonn


AUTHOR



EXTENSIONS

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


STATUS

approved



