%I A064839
%S A064839 1,1,2,1,3,1,4,1,2,2,5,1,6,3,4,1,7,2,8,3,5,6,9,1,3,7,2,4,10,1,11,1,8,9,
%T A064839 10,1,12,11,12,2,13,2,14,5,6,13,15,1,4,7,14,8,16,3,15,4,16,17,17,1,18,
%U A064839 18,9,1,19,3,19,10,20,4,20,1,21,21,11,12,22,5,22,2,2,23,23,2,24,25,26
%N A064839 List the natural numbers starting a new row only with each new least 
               prime signature (A025487). a(n) is the column position associated 
               with n.
%C A064839 Row 2 records the primes (A000040). Rows 3 and 4 record the semiprimes 
               (A001358). Rows 5, 6 and 9 record the 3-almost primes (A014612) etc. 
               A058933 is a similar sequence based on k-almost primes.
%e A064839 The list begins as follows:
%e A064839 1
%e A064839 2 3 5 7 11 13 17 19 23 29 31 37 41 43 47 53 ...
%e A064839 4 9 25 49 ...
%e A064839 6 10 14 15 21 22 26 33 34 35 38 39 46 51 ...
%e A064839 8 27 ...
%e A064839 12 18 20 28 44 45 50 52 ...
%e A064839 16 ...
%Y A064839 A000040, A001358, A014612, A025487 and A058933.
%Y A064839 Sequence in context: A028920 A055396 A057499 this_sequence A094741 A029234 
               A102613
%Y A064839 Adjacent sequences: A064836 A064837 A064838 this_sequence A064840 A064841 
               A064842
%K A064839 easy,nice,nonn
%O A064839 1,3
%A A064839 Alford Arnold (Alford1940(AT)AOL.COM), Oct 24 2001
%E A064839 More terms from Naohiro Nomoto (n_nomoto(AT)yabumi.com), Oct 31 2001