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A035244
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Smallest number with n substrings which are primes.
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1
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1, 2, 13, 23, 113, 137, 373, 1137, 1733, 1373, 11317, 11373, 13733, 31373, 113173, 131373, 137337, 337397, 1113173, 1137337, 1373373, 2337397, 3733797, 11373137, 11373379
(list; graph; refs; listen; history; internal format)
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OFFSET
| 0,2
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COMMENTS
| No leading 0's allowed in substrings.
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EXAMPLE
| a(4)=113 since 3, 11, 13 and 113 are prime and no smaller number works.
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MATHEMATICA
| f[n_] := Block[{s = IntegerDigits[n], c = 0, d = {}}, l = Length[s]; t = Flatten[ Table[ Take[s, {i, j}], {i, 1, l}, {j, i, l}], 1]; k = l(l + 1)/2; While[k > 0, If[ t[[k]][[1]] != 0, d = Append[d, FromDigits[ t[[k]] ]]]; k-- ]; Count[ PrimeQ[d], True]]; a = Table[0, {25}]; Do[ b = f[n]; If[ a[[b + 1]] == 0, a[[b + 1]] = n], {n, 1, 15000000}]; a
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CROSSREFS
| Cf. A079397.
Sequence in context: A195190 A090528 A094535 * A085822 A093301 A079397
Adjacent sequences: A035241 A035242 A035243 * A035245 A035246 A035247
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KEYWORD
| base,easy,nonn
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AUTHOR
| Erich Friedman (erich.friedman(AT)stetson.edu)
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EXTENSIONS
| Edited by Robert G. Wilson v (rgwv(AT)rgwv.com), Feb 25 2003
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