A080154 Values of n corresponding to the terms in sequence A080153.

1, 2, 5, 9, 11, 13, 17, 22, 25, 28, 30, 36, 38, 41, 45, 48, 49, 53, 55, 58, 68, 76, 84, 85, 91, 94, 101, 114, 137, 139, 147, 153, 154, 156, 163, 165, 180, 189, 195, 200, 210, 211, 223, 235, 237, 241, 246, 247, 249, 253, 256, 272, 274, 286, 289, 293, 296, 306, 321, 323

Offset

1,2

Links

Table of n, a(n) for n=1..60.

Formula

For each term a(n) in this sequence, A080153(n) = prime(a(n)).

Example

E.g. the first three terms are 1, 2 and 5 because the concatenation of the first, 2nd and 11th primes is 2311 and this is prime. Also, the 5th prime is the first one after 3 for which this concatenation is prime.

Maple

with(numtheory): pout := [2, 3]: nout := [1, 2]: for n from 3 to 600 do: p := ithprime(n): d := parse(cat(pout[nops(pout)-1], pout[nops(pout)], p)): if (isprime(d)) then pout := [op(pout), p]: nout := [op(nout), n]: fi: od: nout;

Crossrefs

Cf. A073640, A080153.

Sequence in context: A284875 A154732 A242936 * A069829 A022429 A020907

Adjacent sequences: A080151 A080152 A080153 * A080155 A080156 A080157

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