[seqfan] Trappist-1 sequence

W. Edwin Clark wclark at mail.usf.edu
Thu May 18 00:46:39 CEST 2017

I would submit this finite sequence,
but I'm not sure of the proper terminology to describe the sequence.

It comes from this description of the orbits of the f7 Trappist-1 planets.

All seven TRAPPIST-1 planets are locked in what's known as “orbital
> resonance.” Each planet takes a certain amount of time to orbit their sun —
> that's the length of its year. The lengths of the planets' years are
> related to one another in whole-number ratios. So, in the amount of time it
> takes the outermost planet to complete two orbits of the sun, the next
> planet has completed three orbits, the next one four orbits, then six, then
> nine, 15 and 24.

A video and accompanying song can be found here:
> watch-the-delicate-song-and-dance-that-keep-trappist-1-planets-from-blowing-up
> <https://www.washingtonpost.com/news/speaking-of-science/wp/2017/05/11/watch-the-delicate-song-and-dance-that-keep-trappist-1-planets-from-blowing-up/?utm_term=.b662e004d6a4&wpisrc=nl_science&wpmm=1>

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