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A099191
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Smallest prime p such that p+n is twice its reversal, or 0 if impossible.
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0
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73, 2, 3, 0, 5, 0, 7, 0, 0, 0, 11, 0, 211, 0, 0, 0, 53, 0, 613, 0, 0, 0, 0, 0, 43, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 23, 0, 241, 0, 0, 0, 0, 0, 13, 0, 0, 0, 251, 0, 0, 0, 0, 0, 653, 0, 97, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 271, 0, 0, 0, 0, 0, 673, 0, 0, 0, 281, 0, 67, 0, 0, 0, 683, 0, 0, 0, 0
(list; graph; refs; listen; history; internal format)
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OFFSET
| 1,1
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EXAMPLE
| a(13) = 211 since 211+13 = 224 = 2*112. a(25) = 43 since 25+43 = 68 = 2*34.
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MATHEMATICA
| f[n_] := Block[{k = 1}, While[p = Prime[k]; p + n != 2FromDigits[ Reverse[ IntegerDigits[ p]]] && k < 10^6, k++ ]; If[k == 10^6, 0, Prime[k]]]; Table[ f[n], {n, 75}]
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CROSSREFS
| Cf. A099190.
Sequence in context: A028671 A159440 A113889 * A051325 A102050 A057446
Adjacent sequences: A099188 A099189 A099190 * A099192 A099193 A099194
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KEYWORD
| base,nonn
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AUTHOR
| Robert G. Wilson v (rgwv(AT)rgwv.com), Oct 01 2004
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