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A231442
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The digits of a(n) and a(n+1) taken together are the digits of a prime; least permutation of the positive integers with this property.
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3
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1, 3, 2, 9, 5, 11, 8, 12, 4, 7, 6, 10, 13, 15, 14, 17, 18, 16, 19, 21, 22, 30, 20, 23, 24, 29, 26, 27, 25, 31, 28, 33, 32, 35, 36, 34, 37, 39, 38, 41, 42, 43, 45, 47, 44, 51, 40, 49, 46, 57, 50, 53, 48, 59, 56, 63, 52, 61, 54, 67, 55, 69, 58, 70, 60, 71, 62, 72, 64, 73, 66, 79, 75, 65, 74, 68, 77
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OFFSET
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1,2
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LINKS
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M. F. Hasler, in reply to E. Angelini, Two make a prime, SeqFan list, Nov 09 2013
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EXAMPLE
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Start with a(1)=1. The same number cannot be used twice, so the least prime that can be made with this digit is 13, so a(2)=3.
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PROG
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(PARI) {a=1; u=0; for(n=1, 99, u+=1<<a; print1(a", "); for(k=1, 9e9, bittest(u, k)&&next; d=Vec(Str(a, k)); for(p=0, (#d)!-1, isprime(eval(concat(t=vecextract(d, numtoperm(#d, p)))))&&t[1]>"0"&&(a=k)&&next(3))))}
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CROSSREFS
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Cf. A231433 (analog for nonnegative integers).
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KEYWORD
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nonn,base
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AUTHOR
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STATUS
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approved
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