Search: id:A120576
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%I A120576
%S A120576 2,1,3,6,4,12,7,14,28,11,77,5,15,33,55,165,73,146,219,438,9,18,657,1314,
%T A120576 8,16,23,24,36,46,48,69,72,92,138,144,184,207,276,368,414,552,828,1104,
%U A120576 1656,3312,1847,12929,5541,9235,27705,19,38,3694,35093,70186,487,974
%N A120576 Irregular array where the n-th row are the divisors, not occurring earlier 
               in the sequence, of the sum of the terms in all previous rows. a(1)=2.
%C A120576 Is this sequence a permutation of the positive integers?
%H A120576 Leroy Quet, <a href="http://www.prism-of-spirals.net/">Home Page</a> 
               (listed in lieu of email address)
%e A120576 Array begins:
%e A120576 2
%e A120576 1
%e A120576 3
%e A120576 6
%e A120576 4,12
%e A120576 7,14,28
%e A120576 Now these terms add up to 77. So row 7 is the divisors of 77 which do 
               not occur earlier in the sequence. 1 and 7 occur in earlier rows, 
               so row 7 is (11,77).
%t A120576 f[t_] := Flatten[Append[t, Select[Divisors[Plus @@ t], FreeQ[t, # ] &]]]; 
               Nest[f, {2}, 14] (*Chandler*)
%Y A120576 Cf. A120577, A120578, A120579.
%Y A120576 Sequence in context: A125206 A133904 A094339 this_sequence A063707 A118287 
               A024930
%Y A120576 Adjacent sequences: A120573 A120574 A120575 this_sequence A120577 A120578 
               A120579
%K A120576 nonn,tabf
%O A120576 1,1
%A A120576 Leroy Quet Jun 15 2006
%E A120576 Extended by Ray Chandler (rayjchandler(AT)sbcglobal.net), Jun 17 2006

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