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A080153
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a(1)=2, a(2)=3. a(n) for n>2 is the first prime > a(n-1) such that the concatenation of a(n), a(n-1) and a(n-2) is also prime.
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2
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2, 3, 11, 23, 31, 41, 59, 79, 97, 107, 113, 151, 163, 179, 197, 223, 227, 241, 257, 271, 337, 383, 433, 439, 467, 491, 547, 619, 773, 797, 853, 883, 887, 911, 967, 977, 1069, 1129, 1187, 1223, 1291, 1297, 1409, 1483, 1489, 1523, 1559, 1567, 1579, 1607, 1619
(list; graph; refs; listen; history; internal format)
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OFFSET
| 1,1
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EXAMPLE
| E.g. a(3) is the smallest prime > a(2)=3 which, when concatenated to 23 (which is the concatenation of a(1) and a(2)) gives a prime. Thus a(3)=11 because 235 and 237 are composite.
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MAPLE
| with(numtheory): pout := [2, 3]: nout := [1, 2]: for n from 3 to 1000 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: pout;
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CROSSREFS
| Cf. A073640.
Sequence in context: A057135 A104075 A070174 * A040124 A082739 A158017
Adjacent sequences: A080150 A080151 A080152 * A080154 A080155 A080156
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KEYWORD
| nonn,base
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AUTHOR
| Mark Hudson (mrmarkhudson(AT)hotmail.com), Jan 31 2003
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EXTENSIONS
| Edited by Charles R Greathouse IV (charles.greathouse(AT)case.edu), Apr 26 2010
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