login
A087260
a(n) = gcd(4n, A025586(4n)), greatest common divisor of 4n and largest value in 3x+1 iteration list started at 4n.
2
4, 8, 4, 16, 20, 24, 4, 32, 4, 40, 4, 48, 52, 56, 20, 64, 68, 72, 4, 80, 84, 88, 4, 96, 100, 104, 4, 112, 116, 40, 4, 128, 132, 136, 20, 144, 148, 152, 4, 160, 4, 168, 4, 176, 180, 184, 4, 192, 196, 200, 4, 208, 212, 8, 4, 224, 228, 232, 4, 240, 244, 8, 4, 256, 260, 264
OFFSET
1,1
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[4*w, Max[fpl[4*w]]], {w, 1, 256}]
CROSSREFS
KEYWORD
nonn
AUTHOR
Labos Elemer, Sep 09 2003
STATUS
approved