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A317083 a(n) is the first term less than the initial 2n+1 in the reduced Collatz trajectory. 0
1, 1, 1, 5, 7, 5, 5, 5, 13, 11, 1, 5, 19, 23, 11, 23, 25, 5, 7, 19, 31, 37, 17, 23, 37, 29, 5, 47, 43, 19, 23, 61, 49, 19, 13, 61, 55, 1, 29, 19, 61, 47, 1, 37, 67, 61, 35, 91, 73, 7, 19, 61, 79, 91, 41, 61, 85, 65, 11, 101, 91, 59, 47, 77, 97, 37, 25, 43, 103 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,4

LINKS

Table of n, a(n) for n=0..68.

EXAMPLE

a(3)= 5 because, starting with 7, the iteration produces 11,17,13,5 and 5 is the first term less than 7.

MATHEMATICA

f[n_]:=NestWhileList[(3*#+1)/2^IntegerExponent[3*#+1, 2]&, 2*n+1, #>1&];

nextOddK[n_]:=Module[{m=3n+1}, While[EvenQ[m], m=m/2]; m]; dt[n_]:=Module[{m=n, cnt=0}, If[n>1, While[m=nextOddK[m]; cnt++; m>n]]; cnt];

Table[Part[f[i], dt[2i+1]+1], {i, 0, 70}]

CROSSREFS

Cf. A122458, A256598.

Sequence in context: A104542 A161376 A107437 * A122271 A011205 A167133

Adjacent sequences:  A317080 A317081 A317082 * A317084 A317085 A317086

KEYWORD

nonn

AUTHOR

Michel Lagneau, Jul 21 2018

STATUS

approved

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Last modified June 16 06:46 EDT 2019. Contains 324145 sequences. (Running on oeis4.)