Voozh

A087258

a(n) = gcd(n, A025586(n)), greatest common divisor of n and largest value in 3x+1 iteration list started at n.

1, 2, 1, 4, 1, 2, 1, 8, 1, 2, 1, 4, 1, 2, 5, 16, 1, 2, 1, 20, 1, 2, 1, 24, 1, 2, 1, 4, 1, 10, 1, 32, 1, 2, 5, 4, 1, 2, 1, 40, 1, 2, 1, 4, 1, 2, 1, 48, 1, 2, 1, 52, 1, 2, 1, 56, 1, 2, 1, 20, 1, 2, 1, 64, 1, 2, 1, 68, 1, 10, 1, 72, 1, 2, 5, 4, 1, 2, 1, 80, 1, 2, 1, 84, 1, 2, 1, 88, 1, 2, 1, 4, 1, 2, 1, 96, 1

(list; graph; refs; listen; history; text; internal format)

OFFSET

1,2

LINKS

Antti Karttunen, Table of n, a(n) for n = 1..16384

Antti Karttunen, Data supplement: n, a(n) computed for n = 1..100000

Index entries for sequences related to 3x+1 (or Collatz) problem

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] Table[GCD[w, Max[fpl[w]]], {w, 1, 256}]

PROG

(PARI)

A025586(n) = { my(r=n); while(n>2, if(n%2, n=3*n+1; if(n>r, r=n), n/=2)); (r); }; \\ From A025586