Search: id:A008479
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%I A008479
%S A008479 1,1,1,2,1,1,1,3,2,1,1,2,1,1,1,4,1,3,1,2,1,1,1,4,2,1,3,2,1,1,1,5,
%T A008479 1,1,1,5,1,1,1,3,1,1,1,2,2,1,1,6,2,4,1,2,1,7,1,3,1,1,1,2,1,1,2,6,
%U A008479 1,1,1,2,1,1,1,8,1,1,3,2,1,1,1,5,4,1,1,2,1,1,1,3,1,3,1,2,1,1,1,9
%N A008479 Number of numbers <= n with same prime factors as n.
%D A008479 Problem 5735, Amer. Math. Monthly, 78 (1971), 680-681. (Incorrect!)
%D A008479 Problem 5735, Amer. Math. Monthly, 97 (1990), 937.
%H A008479 T. D. Noe, <a href="b008479.txt">Table of n, a(n) for n=1..10000</a>
%t A008479 PkTbl=Prepend[ Array[ Times @@ First[ Transpose[ FactorInteger[ # ] ] 
               ]&, 100, 2 ], 1 ];1+Array[ Count[ Take[ PkTbl, #-1 ], PkTbl[ [ # 
               ] ] ]&, Length[ PkTbl ] ]
%Y A008479 Cf. A005361, A007947.
%Y A008479 Sequence in context: A072411 A091050 A005361 this_sequence A107345 A000688 
               A038538
%Y A008479 Adjacent sequences: A008476 A008477 A008478 this_sequence A008480 A008481 
               A008482
%K A008479 nonn,easy
%O A008479 1,4
%A A008479 Jeffrey Shallit, Olivier Gerard (olivier.gerard(AT)gmail.com)

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