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.

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

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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: A338013 A336190 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