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A072466 Numbers with 11 odd integers in their Collatz (or 3x+1) trajectory. 3
57, 59, 114, 115, 118, 119, 228, 229, 230, 236, 237, 238, 456, 458, 460, 461, 465, 472, 473, 474, 476, 477, 507, 513, 912, 916, 917, 920, 922, 930, 931, 943, 944, 945, 946, 947, 948, 949, 952, 954, 971, 987, 1014, 1015, 1025, 1026, 1027, 1031, 1129, 1131 (list; graph; refs; listen; history; text; internal format)
OFFSET
1,1
COMMENTS
The Collatz (or 3x+1) function is f(x) = x/2 if x is even, 3x+1 if x is odd. The Collatz trajectory of n is obtained by applying f repeatedly to n until 1 is reached.
REFERENCES
J. Shallit and D. Wilson, The "3x+1" Problem and Finite Automata, Bulletin of the EATCS #46 (1992) pp. 182-185.
LINKS
J. Shallit and D. Wilson, The "3x+1" Problem and Finite Automata, Bulletin of the EATCS #46 (1992) pp. 182-185.
MAPLE
b:= proc(n) option remember; irem(n, 2, 'r')+
`if`(n=1, 0, b(`if`(n::odd, 3*n+1, r)))
end:
q:= n-> is(b(n)=11):
select(q, [$1..2000])[]; # Alois P. Heinz, May 18 2022
MATHEMATICA
ocollQ[n_]:=Length[Select[NestWhileList[If[EvenQ[#], #/2, 3#+1]&, n, #>1&], OddQ[#]&]]==11; Select[Range[1140], ocollQ[#]&] (* Jayanta Basu, May 28 2013 *)
CROSSREFS
Column k=11 of A354236.
Sequence in context: A346806 A136542 A042623 * A354170 A345504 A345505
KEYWORD
easy,nonn
AUTHOR
Jim Nastos, Jun 19 2002
STATUS
approved

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Last modified September 22 01:06 EDT 2023. Contains 365503 sequences. (Running on oeis4.)