[math-fun] A sequence puzzle

Michael Kleber michael.kleber at gmail.com
Mon Jul 31 20:53:39 CEST 2006

Franklin T. Adams-Watters asks:
> 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.

An OEIS search for the number 27720 will be enough to give it away,
for anyone who's stumped.

Well, I think you haven't gone quite far enough to give us the full rule.
>From where you left off, I believe the next run-up in your sequence is
5, 105, 2310, 53130, 212520, 1062600, 13813800, 124324200
But is the next thing after that 6 or 7?

--Michael Kleber

It is very dark and after 2000.
If you continue you are likely to be eaten by a bleen.

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