A080156 - OEIS

A080156

Values of n corresponding to the terms in sequence A080155. For any k, the concatenation of the a(1) to a(k)-th primes is prime and each value of k is the smallest for which this is true.

%I #8 Apr 12 2014 02:17:39

%S 1,2,5,11,15,50,54,106,148,149,156,188,200,211,248,326,359,374,417,

%T 467,699,798,891,966,1038,1519,1542,1578,1831,1908,1982,2079,2305,

%U 2640,2660,2845,3078,3145,3760,3777,3835,4538,4630,4991,5019,5554,5658,5827

%N Values of n corresponding to the terms in sequence A080155. For any k, the concatenation of the a(1) to a(k)-th primes is prime and each value of k is the smallest for which this is true.

%H T. D. Noe, <a href="/A080156/b080156.txt">Table of n, a(n) for n = 1..201</a>

%F a(n) = prime(A080155(n)).

%p with(numtheory): pout := [2]: nout := [1]: for n from 2 to 5000 do: p := ithprime(n): d := parse(cat(seq(pout[i],i=1..nops(pout)),p)): if (isprime(d)) then pout := [op(pout),p]: nout := [op(nout),n]: fi: od: nout;

%Y Cf. A073640, A080152-A080155.

%K nonn,base

%O 1,2

%A Mark Hudson (mrmarkhudson(AT)hotmail.com), Jan 31 2003

%E Edited by _Charles R Greathouse IV_, Apr 30 2010