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%I #11 Jan 27 2020 08:27:25
%S 2,2,2,2,3,3,3,2,2,4,2,1,3,3,2,2,3,2,2,4,3,2,4,2,2,3,3,4,4,3,2,4,3,2,
%T 5,2,2,4,1,3,3,4,2,3,3,2,3,3,3,4,3,3,2,3,5,3,3,1,4,4,2,4,2,2,5,2,4,3,
%U 3,3,3,4,2,4,3,2,3,2,2,3,4,3,3,2,3,6,4
%N Number of distinct prime divisors of numbers from four consecutive concatenated odd numbers.
%C Interestingly, 23252729 is prime.
%H Amiram Eldar, <a href="/A104186/b104186.txt">Table of n, a(n) for n = 1..10000</a>
%e The number of distinct prime factors of 1357 is 2 - the first term in the sequence.
%e The number of distinct prime factors of 3579 is 2 - the second term in the sequence.
%e The number of distinct prime factors of 57911 is 2 - the third term in the sequence.
%t a[n_] := PrimeNu@ FromDigits @ (Join @@ IntegerDigits /@ (2*n + {-1, 1, 3, 5})); Array[a, 100] (* _Amiram Eldar_, Jan 27 2020 *)
%Y Cf. A001221, A104377.
%K nonn,base
%O 1,1
%A _Parthasarathy Nambi_, Apr 16 2005
%E Offset corrected and more terms added by _Amiram Eldar_, Jan 27 2020
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