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 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. 2
 1, 2, 5, 11, 15, 50, 54, 106, 148, 149, 156, 188, 200, 211, 248, 326, 359, 374, 417, 467, 699, 798, 891, 966, 1038, 1519, 1542, 1578, 1831, 1908, 1982, 2079, 2305, 2640, 2660, 2845, 3078, 3145, 3760, 3777, 3835, 4538, 4630, 4991, 5019, 5554, 5658, 5827 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,2 LINKS T. D. Noe, Table of n, a(n) for n = 1..201 FORMULA a(n) = prime(A080155(n)). MAPLE 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; CROSSREFS Cf. A073640, A080152-A080155. Sequence in context: A003420 A206602 A238159 * A082083 A287558 A024917 Adjacent sequences:  A080153 A080154 A080155 * A080157 A080158 A080159 KEYWORD nonn,base AUTHOR Mark Hudson (mrmarkhudson(AT)hotmail.com), Jan 31 2003 EXTENSIONS Edited by Charles R Greathouse IV, Apr 30 2010 STATUS approved

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Last modified January 20 08:18 EST 2020. Contains 331081 sequences. (Running on oeis4.)