A084667 Primes which are a concatenation of n and prime(n).

23, 47, 613, 1237, 1759, 1861, 2383, 27103, 30113, 35149, 36151, 41179, 42181, 45197, 46199, 54251, 56263, 57269, 58271, 61283, 71353, 82421, 83431, 85439, 92479, 93487, 99523, 115631, 117643, 119653, 121661, 123677, 127709, 136769, 141811, 145829, 147853

Offset: 1

Author

Zak Seidov, Jun 29 2003

Keywords

• nonn
• base

Comments

Is the sequence infinite? - Zak Seidov, Nov 19 2013

Examples

			a(3) = 613 because prime(6) = 13 and 613 is prime,
a(1000) = 761077477 because prime(7610) = 77477 and 761077477 is prime.
a(20000) = 2092142886529 because prime(209214) = 2886529 and 2092142886529 is prime.
		

Links

• Zak Seidov, Table of n, a(n) for n = 1..20000

Crossrefs

Cf. A084669.

Programs

Magma

[p: n in [1..200] | IsPrime(p) where p is Seqint(Intseq(NthPrime(n)) cat Intseq(n))]; // Bruno Berselli, Sep 15 2015

Mathematica

Select[Table[FromDigits[Flatten[{IntegerDigits[n], IntegerDigits[Prime[n]]}]], {n, 1, 500}], PrimeQ] (* Alonso del Arte, Sep 22 2004 *)

PARI

lista(NN) = for(k=1,NN,p=prime(k);if(isprime(j=k*10^#digits(p)+p),print1(j, ", "))) \\ Jinyuan Wang, Apr 05 2019