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A069566
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a(n) = smallest value of k such that the concatenation 1,n,n^2,..., n^(k-1), n^k,n^(k-1),...n^2,n,1 is a prime.
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0
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OFFSET
| 1,2
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COMMENTS
| Program and terms from Robert G. Wilson v.
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EXAMPLE
| a(2) = 2 as 12421 is a prime.
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MATHEMATICA
| Do[k = 0; While[a = Table[n^i, {i, 0, k}]; b = ToExpression[ StringJoin[ ToString /@ Join[a, Drop[ Reverse[a], 1]]]]; !PrimeQ[b], k++ ]; Print[b], {n, 2, 10} ]
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CROSSREFS
| Sequence in context: A107049 A074956 A176088 * A066818 A005730 A112284
Adjacent sequences: A069563 A069564 A069565 * A069567 A069568 A069569
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KEYWORD
| more,nonn,base
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AUTHOR
| Amarnath Murthy (amarnath_murthy(AT)yahoo.com), Mar 24 2002
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