OFFSET
2,1
LINKS
Rémy Sigrist, Table of n, a(n) for n = 2..10000
MATHEMATICA
c[x_] := (1-Mod[x, 2])*(x/2)+Mod[x, 2]*(3*x+1); c[1]=1; fpl[x_] := Delete[FixedPointList[c, x], -1] ofp[x_] := Part[fpl[x], Flatten[Position[PrimeQ[fpl[x]], True]]] Table[Max[ofp[w]], {w, 1, 256}]
Table[Max[Select[NestWhileList[If[EvenQ[#], #/2, 3#+1]&, n, #>1&], PrimeQ]], {n, 2, 70}] (* Harvey P. Dale, Feb 27 2023 *)
PROG
(PARI) a(n) = my (mx=2); while (n>1, if (isprime(n), mx=max(mx, n)); n=if (n%2, 3*n+1, n/2)); mx \\ Rémy Sigrist, Oct 08 2018
CROSSREFS
KEYWORD
nonn
AUTHOR
Labos Elemer, Sep 18 2003
EXTENSIONS
Offset corrected by Rémy Sigrist, Oct 08 2018
STATUS
approved