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 A102745 Number of distinct prime factors of four consecutively concatenated primes. 1
 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; text; internal format)
 OFFSET 1,2 LINKS Harvey P. Dale, Table of n, a(n) for n = 1..1000 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. MATHEMATICA f[n_] := Length[ FactorInteger[ FromDigits[ Flatten[ Table[ IntegerDigits[ Prime[i]], {i, n, n + 3}]] ]]]; Table[ f[n], {n, 105}] (* Robert G. Wilson v, Feb 22 2005 *) PrimeNu[FromDigits[Flatten[IntegerDigits/@#]]]&/@Partition[ Prime[ Range[ 120]], 4, 1] (* Harvey P. Dale, Mar 07 2020 *) CROSSREFS Sequence in context: A293072 A120447 A083021 * A108026 A010702 A095925 Adjacent sequences:  A102742 A102743 A102744 * A102746 A102747 A102748 KEYWORD nonn,base AUTHOR Parthasarathy Nambi, Feb 08 2005 EXTENSIONS More terms from Robert G. Wilson v, Feb 22 2005 STATUS approved

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Last modified September 21 14:54 EDT 2020. Contains 337272 sequences. (Running on oeis4.)