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 A267703 Conjectured list of numbers whose trajectory under the '7x+1' map eventually reaches 1. 2
 1, 2, 4, 5, 8, 9, 10, 16, 18, 20, 32, 36, 40, 41, 64, 72, 73, 80, 82, 128, 144, 146, 160, 164, 167, 256, 288, 292, 320, 328, 329, 334, 512, 576, 584, 585, 640, 656, 658, 668, 1024, 1152, 1168, 1170, 1280, 1312, 1316, 1336, 1337, 1965, 2048, 2304, 2336, 2340, 2560 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,2 COMMENTS This is conjectural in that there is no known proof that the missing numbers 3, 6, 7, ... are really missing. It may be that after a very large number of iterations they will cycle. - N. J. A. Sloane, Jan 23 2016 Note that the computer program does not actually calculate a complete list of "numbers k such that the Collatz-like map T: if x odd, x -> 7*x+1 and if x even, x -> x/2, when started at k, eventually reaches 1". LINKS Dmitry Kamenetsky, Table of n, a(n) for n = 1..164 EXAMPLE 5 is in the sequence because the trajectory of 5 is 5 -> 36 -> 18 -> 9 -> 64 -> 32 -> 16 -> 8 -> 4 -> 2 -> 1. MAPLE nn:=10000: for n from 1 to 2340 do: m:=n:cyc:={n}: for i from 1 to nn do: if irem(m, 2)=0 then m:=m/2: else m:=7*m+1: fi: cyc:=cyc union {m}: od: n0:=nops(cyc): if n0

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Last modified August 13 20:30 EDT 2024. Contains 375144 sequences. (Running on oeis4.)