[seqfan] Do we have this?

Frank Adams-Watters franktaw at netscape.net
Thu Jul 7 21:02:15 CEST 2016


https://brilliant.org/practice/linear-recurrence-relations-level-4-5-challenges/?problem=are-you-ready-for-brimo&utm_medium=social&utm_source=facebook&utm_campaign=adv_fb_posts_07062016&utm_content=qq_ch_linear_recurrence_l45

(You have to register with them to see their answer; but see below, I'm sure that their answer is not correct.)

There is an obvious sequence for, the same problem for 2n people. If I haven't made a mistake, this should start with 0*1!, 1*2!, 4*3!, 29*4! = 0, 2, 24, 696, which is not in the database. (The n! term comes from permuting the tests without changing the pattern in which they are handed out.) Looking only at 2, 24, 696 gives A030438 as the only match; while this seems similar, I don't think it is actually the correct sequence.

The search dividing out the n! factor gives too many matches to look through.

The linked site claims the next term is 1048580, but this can't be correct; it is not a multiple of 5!.

So first, is my 29 correct? Second, is this sequence in the database? If not, can someone compute a few terms?

Franklin T. Adams-Watters



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