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A238193 Position of first occurrence of (4^n - 1)/3 in A238192. 1
3, 21, 75, 151, 1365, 5461, 14563, 87381, 184111, 932067 (list; graph; refs; listen; history; text; internal format)
OFFSET

2,1

COMMENTS

Another version of A237661.

Is this (apart from the missing 1) the same as A054646?  - R. J. Mathar, Mar 30 2014

LINKS

Table of n, a(n) for n=2..11.

MATHEMATICA

Collatz[n_] := NestWhileList[If[EvenQ[#], #/2, 3 # + 1] &, n, # > 1 &]; t = Table[c = Collatz[n]; co = Select[c, OddQ]; If[Length[co] == 1, 0, co[[-2]]], {n, 10000}]; Flatten[Table[Position[t, (4^n - 1)/3, 1, 1], {n, 2, 7}]]

CROSSREFS

Cf. A002450 ((4^n-1)/3), A070165 (Collatz trajectories), A238192.

Sequence in context: A188667 A083564 A281008 * A054646 A228317 A322228

Adjacent sequences:  A238190 A238191 A238192 * A238194 A238195 A238196

KEYWORD

nonn,more

AUTHOR

T. D. Noe, Feb 21 2014

STATUS

approved

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Last modified June 21 18:22 EDT 2021. Contains 345365 sequences. (Running on oeis4.)