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A102745
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Number of distinct prime factors of four consecutively concatenated primes.
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0
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1, 3, 4, 3, 4, 3, 3, 2, 3, 2, 3, 3, 3, 4, 4, 3, 3, 4, 1, 2, 4, 3, 1, 3, 4, 3, 4, 4, 3, 2, 5, 2, 3, 1, 1, 2, 2, 2, 2, 2, 3, 5, 3, 2, 4, 4, 2, 3, 5, 4, 3, 4, 3, 5, 3, 3, 3, 2, 4, 2, 4, 3, 3, 3, 4, 4, 2, 3, 2, 3, 2, 3, 2, 4, 3, 1, 2, 4, 3, 3, 3, 4, 4, 2, 4, 3, 4, 5, 4, 4, 2, 4, 5, 4, 3, 1, 3, 3, 4, 3, 4, 1, 2, 3, 4
(list; graph; refs; listen; history; internal format)
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OFFSET
| 1,2
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EXAMPLE
| 2357 is a prime, thus the number of distinct prime factors is 1.
The number of distinct prime factors of 31374143 is 3.
67717379 is prime, thus the number of distinct prime factors is 1.
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MATHEMATICA
| f[n_] := Length[ FactorInteger[ FromDigits[ Flatten[ Table[ IntegerDigits[ Prime[i]], {i, n, n + 3}]] ]]]; Table[ f[n], {n, 105}] (from Robert G. Wilson v Feb 22 2005)
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CROSSREFS
| Sequence in context: A120447 A083021 A027684 * A108026 A010702 A095925
Adjacent sequences: A102742 A102743 A102744 * A102746 A102747 A102748
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KEYWORD
| nonn,base
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AUTHOR
| Parthasarathy Nambi (PachaNambi(AT)yahoo.com), Feb 08 2005
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EXTENSIONS
| More terms from Robert G. Wilson v (rgwv(AT)rgwv.com), Feb 22 2005
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