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A084667 Primes which are a concatenation of n and prime(n). 8
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 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

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

LINKS

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

EXAMPLE

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.

MATHEMATICA

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

PROG

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

(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

CROSSREFS

Cf. A084669.

Sequence in context: A247673 A216569 A042054 * A255596 A157358 A158238

Adjacent sequences:  A084664 A084665 A084666 * A084668 A084669 A084670

KEYWORD

nonn,base

AUTHOR

Zak Seidov, Jun 29 2003

STATUS

approved

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Last modified June 16 06:46 EDT 2019. Contains 324145 sequences. (Running on oeis4.)