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A071263
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Smallest nontrivial composite number beginning with n.
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1
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12, 21, 33, 42, 51, 62, 72, 81, 91, 102, 111, 121, 132, 141, 152, 161, 171, 182, 192, 201, 212, 221, 231, 242, 252, 261, 272, 282, 291, 301, 312, 321, 332, 341, 351, 361, 371, 381, 391, 402, 411, 422, 432, 441, 451, 462, 471, 481, 492, 501, 511, 522, 531
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OFFSET
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1,1
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COMMENTS
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Nontrivial means that simply appending a 0 to n is not allowed, nor is n itself.
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LINKS
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Table of n, a(n) for n=1..53.
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MATHEMATICA
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a[n_] := (j = ToString[n]; l = {"1", "2", "3", "4", "5", "6", "7", "8", "9", "01", "02", "03", "04", "05", "06", "07", "08", "09"}; k = 1; While[c = ToExpression[ StringJoin[j, ToString[ l[[k]] ]]]; k < 19 && PrimeQ[c], k++ ]; If[k < 19, Return[c]]; i = IntegerDigits[n]; k = 10; While[c = FromDigits[ Join[i, IntegerDigits[k]]]; PrimeQ[c], k++ ]; Return[c]); Table[ a[n], {n, 1, 55}]
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CROSSREFS
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Cf. A071262.
Sequence in context: A316266 A179899 A085926 * A241503 A226186 A325301
Adjacent sequences: A071260 A071261 A071262 * A071264 A071265 A071266
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KEYWORD
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nonn,base,easy
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AUTHOR
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Amarnath Murthy, May 30 2002
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EXTENSIONS
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Edited by Robert G. Wilson v, Jun 14 2002
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STATUS
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approved
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