Search: id:A048672
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%I A048672
%S A048672 0,1,2,4,3,8,5,16,32,9,6,64,128,10,17,256,33,512,7,1024,18,65,12,2048,
%T A048672 129,34,4096,11,8192,257,16384,66,32768,20,130,513,65536,131072,1025,
%U A048672 36,19,262144,258,13,524288,1048576,2049,24,35,2097152,4097,4194304,68
%N A048672 Binary encoding of square-free numbers (A005117) A048640[ n ]/2.
%C A048672 Permutation of A001477 (nonnegative integers). Shares with A048639 and 
               A048623 the property that even numbers turn to odd encodings and 
               vice versa.
%C A048672 Inverse of sequence A064273 considered as a permutation of the nonnegative 
               integers. - Howard A. Landman (howard(AT)polyamory.org), Sep 25 2001
%C A048672 Also index of n-th term of A019565 when its terms are sorted in increasing 
               order. For example: a(6) = 8. The smallest values of A019565 are 
               1,2,3,5,6,7 . The 6th is 7 which is A019565(8). - Philippe Lallouet 
               (philip.lallouet(AT)orange.fr), Apr 28 2008
%H A048672 <a href="Sindx_Per.html#IntegerPermutation">Index entries for sequences 
               that are permutations of the natural numbers</a>
%F A048672 a(n) = 2^(i1-1)+2^(i2-1)+...+2^(iz-1), where A005117[ n ] = p_i1*p_i2*p_i3*...*p_iz
%p A048672 encode_sqrfrees := proc(upto_n) local b,i; b := [ ]; for i from 1 to 
               upto_n do if(0 <> mobius(i)) then b := [ op(b), bef(i) ]; fi; od: 
               RETURN(b); end; # see A048623 for bef
%Y A048672 Cf. A005117, A048639, A048640, A048623.
%Y A048672 Cf. A019565.
%Y A048672 Sequence in context: A118783 A120242 A054427 this_sequence A127301 A122111 
               A153212
%Y A048672 Adjacent sequences: A048669 A048670 A048671 this_sequence A048673 A048674 
               A048675
%K A048672 easy,nonn
%O A048672 1,3
%A A048672 Antti Karttunen, Jul 14 1999

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