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%I #8 Nov 21 2013 12:48:40
%S 1,2,1,2,2,2,2,2,3,1,2,1,1,4,2,1,3,1,2,2,2,2,2,2,2,3,1,1,3,1,1,2,2,2,
%T 3,3,2,3,2,2,3,2,2,3,2,1,2,2,2,2,1,2,2,2,1,3,1,2,4,2,2,2,2,2,3,2,3,2,
%U 3,1,2,1,1,3,2,1,2,1,3,3,1,2,3,3,1,4,2,2,3,1,1,2,3,3,2,1,2,4,4,2,2,1,2,3,1
%N Number of distinct prime factors of the concatenation of two consecutive odd numbers.
%C Each odd number is used only once, i.e., although (1,3) and (5,7) are both treated as two consecutive odd numbers, (3,5) and (7,9) are not. [From Harvey P. Dale, Jul 13 2011]
%e a(1) =omega(13) = 1; a(2) = omega(57) = 2; a(3) = omega(911) = 1.
%t f[n_]:=PrimeNu[FromDigits[Flatten[IntegerDigits/@{First[n], Last[n]}]]]; f/@Partition[Range[1,421,2],2] (* _Harvey P. Dale_, Jul 13 2011 *)
%o (PARI) a(n)=omega(eval(Str(4*n-3,4*n-1)))
%K nonn,base
%O 1,2
%A _Parthasarathy Nambi_, Apr 11 2005
%E Extended, corrected, and edited by _Charles R Greathouse IV_, Apr 27 2010
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