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 A075477 Number of iteration that first becomes smaller than the initial value if Collatz-function (A006370) is iterated, starting with numbers of form 64n+15. Corresponds to selection of every 16th term from A074474. 3
 12, 14, 12, 22, 12, 14, 12, 20, 12, 14, 12, 22, 12, 14, 12, 17, 12, 14, 12, 20, 12, 14, 12, 40, 12, 14, 12, 58, 12, 14, 12, 17, 12, 14, 12, 33, 12, 14, 12, 33, 12, 14, 12, 25, 12, 14, 12, 17, 12, 14, 12, 33, 12, 14, 12, 27, 12, 14, 12, 40, 12, 14, 12, 17, 12, 14, 12, 69, 12 (list; graph; refs; listen; history; text; internal format)
 OFFSET 0,1 COMMENTS Remark that initial values of form 64m+r, if r={3,11,19,27,35,43,51,55} provide first-sink-lengths {7,9,7,9,7,9,7,9} respectively; e.g. {64k+19,192k+58,96k+29,288k+88,144k+44,72k+22,36k+11} submerge first below initial value at the 7th term,36k+11<64k+19. LINKS Antti Karttunen, Table of n, a(n) for n = 0..16384 FORMULA a(n) = A074473(64n+15), n=0..256. [corrected by Antti Karttunen, Oct 09 2018] EXAMPLE n=0: 64n+15=15,list={15,46,23,70,35,106,53,160,80,40,20,10..}, i.e. the 12th term is the first that <15, the initial value. PROG (PARI) A006370(n) = if(n%2, 3*n+1, n/2); A074473(n) = if(1==n, n, my(org_n=n); for(i=1, oo, if(n

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Last modified April 19 10:30 EDT 2021. Contains 343112 sequences. (Running on oeis4.)