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A237661
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Indices of records in A237660.
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3
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3, 42, 75, 151, 2730, 7281, 14563, 174762, 184111, 932067, 11184810, 13256071, 26512143, 715827882, 1908874353
(list;
graph;
refs;
listen;
history;
text;
internal format)
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OFFSET
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1,1
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LINKS
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MATHEMATICA
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With[{s = Table[If[AllTrue[#, EvenQ], 0, SelectFirst[Reverse@ #, OddQ]] &@ Most@ Rest@ NestWhileList[If[EvenQ@ #, #/2, (3 # + 1)/2] &, n, # > 1 &], {n, 2, 10^5}] }, 1 + Values[#][[All, 1]] &@ Rest@ KeySort@ PositionIndex@ s] (* Michael De Vlieger, Aug 14 2017 *)
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PROG
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(C) See Greathouse link
(PARI) A237660(n)=my(k); if(n%2, n=3*n+1); n>>=valuation(n, 2); if(n==1, return(0)); k=n; while(1, n+=(n+1)>>1; n>>=valuation(n, 2); if(n==1, return(k), k=n))
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CROSSREFS
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KEYWORD
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nonn,more
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AUTHOR
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EXTENSIONS
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STATUS
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approved
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