A046460 - OEIS

%I #28 Sep 04 2021 10:07:43

%S 0,3,2,2,3,8,2,5,4,3,6,6,3,3,3,4,5,6,6,10,8,6,4,6,5,9,8,7,4,7,3,6,6,2,

%T 8,9,4,4,6,9,5,7,4,7,10,7,5,8,6,10,3,9,8,14,5,5,6,4,4,8,3,8,5,10,6,8,

%U 3,10,7,6,6,7,3,9,6,6,5,6,6,10,6,7,6,7,6

%N Number of prime factors of concatenation of numbers from 1 up to n, with multiplicity.

%H Patrick De Geest, <a href="http://www.worldofnumbers.com/factorlist.htm">Normal Smarandache Concatenated Numbers, Prime factors from 1 up to n</a>

%H M. Fleuren, <a href="http://www.gallup.unm.edu/~smarandache/michafleuren.htm">Factors and primes of Smarandache sequences</a>.

%H M. Fleuren, <a href="http://www.gallup.unm.edu/~smarandache/micha.txt">Smarandache Factors and Reverse factors</a>

%H Carlos Rivera, <a href="http://www.primepuzzles.net/puzzles/puzz_008.htm">Puzzle 8. Primes by Listing</a>, The Prime Puzzles & Problems Connection.

%t Join[{1},Table[PrimeOmega[FromDigits[Flatten[IntegerDigits[Range[i]]]]],{i,2,35}]] (* _Jayanta Basu_, Jun 02 2013 *)

%o (PARI) conc(n) = my(s=""); for(k=1, n, s=Str(s, k)); eval(s); \\ A007908

%o a(n) = bigomega(conc(n)); \\ _Michel Marcus_, Oct 16 2019

%Y Cf. A007908, A046461, A046462, A046463, A046464, A046465, A046466, A046467, A046468, A048288.

%K nonn,hard,base

%O 1,2

%A _Patrick De Geest_, Aug 15 1998

%E Offset 1 and a(1)=0 from _Michel Marcus_, Oct 16 2019

%E More terms from _Sean A. Irvine_, Apr 10 2021