A237661 Indices of records in A237660.

3, 42, 75, 151, 2730, 7281, 14563, 174762, 184111, 932067, 11184810, 13256071, 26512143, 715827882, 1908874353

Offset: 1

Author

Kival Ngaokrajang, Feb 11 2014

Keywords

• nonn
• more

Links

• Charles R Greathouse IV, C code to find initial terms

Crossrefs

Cf. A237660.

Programs

C

See Greathouse link

Mathematica

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 *)

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))
r=0; for(n=1,1e8, t=A237660(n); if(t>r, r=t; print1(n", "))) \\ Charles R Greathouse IV, Aug 14 2017

Extensions

a(11)-a(15) from Charles R Greathouse IV, Aug 14 2017