A087260 a(n) = gcd(4n, A025586(4n)), greatest common divisor of 4n and largest value in 3x+1 iteration list started at 4n.

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

Links

Table of n, a(n) for n=1..66.

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

Cf. A025586, A033496-A087261.

Sequence in context: A377397 A059159 A028587 * A019254 A304293 A055374

Adjacent sequences: A087257 A087258 A087259 * A087261 A087262 A087263

Keyword

nonn

Author

Labos Elemer, Sep 09 2003

Status

approved