# Greetings from The On-Line Encyclopedia of Integer Sequences! http://oeis.org/ Search: id:a071823 Showing 1-1 of 1 %I A071823 #8 Jun 29 2017 11:50:35 %S A071823 0,0,1,1,1,2,3,3,4,4,5,6,6,7,7,7,7,8,9,9,10,11,12,13,13,13,14,15,15, %T A071823 15,16,16,17,17,18,19,19,20,20,20,20,21,22,23,23,24,25,26,27,27,27,27, %U A071823 27,28,29,30,31,31,32,32,32,33,34,34,34,35,36,36,37,38,39,40,40,40,40,41 %N A071823 Number of numbers x <= n with largest prime factor of the form 4k+3. %C A071823 Conjecture : for n > 1000, a(n) - n/2 > sqrt(n). %t A071823 Accumulate[Table[If[Mod[FactorInteger[n][[-1,1]],4]==3,1,0],{n,80}]] (* _Harvey P. Dale_, Jun 29 2017 *) %o A071823 (PARI) for(n=2,200,print1(sum(i=2,n,if((component(component(factor(i),1),omega(i))-3)%4,0,1)),",")) %K A071823 easy,nonn %O A071823 1,6 %A A071823 _Benoit Cloitre_, Jun 07 2002 %E A071823 Zero prepended by _Harvey P. Dale_, Jun 29 2017 # Content is available under The OEIS End-User License Agreement: http://oeis.org/LICENSE