OFFSET
1,1
COMMENTS
Is this sequence a permutation of the positive integers?
EXAMPLE
Array begins:
4
1,2
7
14
28
8,56
Now these terms add up to 120. So row 7 is the divisors of 120 which do not occur earlier in the sequence. 1,2,4 and 8 occur in earlier rows, so row 7 is (3,5,6,10,12,15,20,24,30,40,60,120).
MATHEMATICA
f[t_] := Flatten[Append[t, Select[Divisors[Plus @@ t], FreeQ[t, # ] &]]]; Nest[f, {4}, 12] (* Ray Chandler, Jun 17 2006 *)
CROSSREFS
KEYWORD
nonn,tabf
AUTHOR
Leroy Quet, Jun 15 2006
EXTENSIONS
Extended by Ray Chandler, Jun 17 2006
STATUS
approved