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A117840
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Smaller of two consecutive prime numbers with the same multiplicative digital root.
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1
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79, 101, 103, 107, 151, 163, 179, 197, 211, 229, 251, 271, 281, 293, 349, 379, 401, 419, 443, 491, 503, 509, 521, 523, 541, 563, 577, 599, 601, 613, 631, 653, 691, 701, 769, 821, 853, 857, 881, 997, 1009, 1013, 1019, 1021, 1031, 1033, 1039, 1049, 1051, 1061
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history;
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internal format)
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OFFSET
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1,1
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LINKS
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Amiram Eldar, Table of n, a(n) for n = 1..10000
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EXAMPLE
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79 and 83 are two consecutive primes with the same multiplicative digital root, namely 8.
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MATHEMATICA
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pod[n_] := Times @@ IntegerDigits[n]; multDigRoot[n_] := NestWhile[pod, n, # > 9 &]; Select[Partition[Select[Range[1000], PrimeQ], 2, 1], Equal @@ multDigRoot /@ # &][[;; , 1]] (* Amiram Eldar, Feb 06 2021 *)
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CROSSREFS
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Cf. A031347, A199975.
Sequence in context: A106757 A285228 A087537 * A296012 A193142 A033250
Adjacent sequences: A117837 A117838 A117839 * A117841 A117842 A117843
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KEYWORD
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base,nonn
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AUTHOR
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Luc Stevens (lms022(AT)yahoo.com), Apr 30 2006
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STATUS
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approved
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