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 A075476 Number of iteration that first becomes smaller than the initial value if Collatz-function (A006370) is iterated, starting with numbers of form 64n+7. Corresponds to selection of every 16th term from A074474. 10
 12, 84, 12, 14, 12, 35, 12, 14, 12, 17, 12, 14, 12, 25, 12, 14, 12, 25, 12, 14, 12, 27, 12, 14, 12, 17, 12, 14, 12, 38, 12, 14, 12, 25, 12, 14, 12, 45, 12, 14, 12, 17, 12, 14, 12, 27, 12, 14, 12, 20, 12, 14, 12, 79, 12, 14, 12, 17, 12, 14, 12, 20, 12, 14, 12, 33, 12, 14, 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+7), n=0, ..., 256 EXAMPLE n=0: 64n+7=7, list={7, 22, 11, 34, 17, 52, 26, 13, 40, 20, 10, 5..}, i.e. the 12th term is the first that <12, the initial value. MATHEMATICA lcoll[n_] := Length[NestWhileList[If[EvenQ[#], #/2, 3 # + 1] &, n, # >= n &]]; Table[lcoll[64*i + 7], {i, 0, 68}] (* Jayanta Basu, Jun 15 2013 *) 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 May 5 22:32 EDT 2021. Contains 343578 sequences. (Running on oeis4.)