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%I #11 Mar 07 2020 13:07:42
%S 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,
%T 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,
%U 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
%N Number of distinct prime factors of four consecutively concatenated primes.
%H Harvey P. Dale, <a href="/A102745/b102745.txt">Table of n, a(n) for n = 1..1000</a>
%e 2357 is a prime, thus the number of distinct prime factors is 1.
%e The number of distinct prime factors of 31374143 is 3.
%e 67717379 is prime, thus the number of distinct prime factors is 1.
%t 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 *)
%t PrimeNu[FromDigits[Flatten[IntegerDigits/@#]]]&/@Partition[ Prime[ Range[ 120]],4,1] (* _Harvey P. Dale_, Mar 07 2020 *)
%K nonn,base
%O 1,2
%A _Parthasarathy Nambi_, Feb 08 2005
%E More terms from _Robert G. Wilson v_, Feb 22 2005
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