31 Jul
2006
31 Jul
'06
12:53 p.m.
On 7/31/06, franktaw@netscape.net <franktaw@netscape.net> wrote:
Here are the first 20 terms of a sequence:
1,2,6,12,60,3,21,168,504,2520,27720,4,52,364,5460,21840,371280,1113840, 21162960,5
The puzzle is to determine the rule of formation.
LCM with the next natural; if you get the same number twice, replace with the next unseen natural (1,2) = 2 (2,3) = 6 (6,4) = 12 (12,5) = 60 (60,6) = 60, so replace this with the first natural we haven't seen yet. We already have 1,2, so choose 3 (3,7)=21 (21,8)=168 etc.. (27720,12)=27720, so go to 4.
Franklin T. Adams-Watters -- Mike Stay metaweta@gmail.com http://math.ucr.edu/~mike