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A046035 Numbers n such that the concatenation of the first n primes (A019518) is a prime. 10
1, 2, 4, 128, 174, 342, 435, 1429 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

COMMENTS

The primes themselves (A069151) are sometimes called Smarandache-Wellin primes.

No others with n <= 10400. - Eric W. Weisstein, Mar 01 2004

REFERENCES

R. Crandall and C. Pomerance, Prime Numbers: A Computational Perspective, Springer, NY, 2001; see p. 72. [The 2002 printing states incorrectly that 719 is a term.]

LINKS

Table of n, a(n) for n=1..8.

M. Fleuren, Smarandache Concatenated Primes.

Eric Weisstein's World of Mathematics, Integer Sequence Primes

Eric Weisstein's World of Mathematics, Consecutive Number Sequences

EXAMPLE

4 is a term since 2357 is a prime. [Corrected by Ed Murphy (emurphy42(AT)socal.rr.com), May 15 2007]

MATHEMATICA

a = ""; Do[a = StringJoin[a, ToString[ Prime[n]]]; If[ PrimeQ[ ToExpression[a ]], Print[n]], {n, 1, 1429}]

nn=1500; With[{prs=Prime[Range[nn]]}, Flatten[Position[Table[ FromDigits[ Flatten[ IntegerDigits/@Take[prs, n]]], {n, nn}], _?PrimeQ]]] (* Harvey P. Dale, Dec 17 2013 *)

CROSSREFS

Cf. A019518, A033308, A069151. A046284(n) = prime(a(n)).

Sequence in context: A006314 A009595 A018493 * A134710 A009073 A012561

Adjacent sequences:  A046032 A046033 A046034 * A046036 A046037 A046038

KEYWORD

nonn,base,nice

AUTHOR

Eric W. Weisstein

STATUS

approved

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Last modified September 22 18:27 EDT 2014. Contains 247074 sequences.