A087260 -id:A087260 - cp's OEIS frontend

A087261 a(n) = lcm(4n, A025586(4n)), least common multiple of 4n and the largest value in 3x+1 iteration list started at 4n.

4, 8, 48, 16, 20, 24, 364, 32, 468, 40, 572, 48, 52, 56, 480, 64, 68, 72, 1672, 80, 84, 88, 3680, 96, 100, 104, 249264, 112, 116, 480, 286192, 128, 132, 136, 1120, 144, 148, 152, 11856, 160, 378512, 168, 8428, 176, 180, 184, 433904, 192, 196, 200, 11832, 208, 212

Offset: 1

Labos Elemer, Sep 09 2003

nonn

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

Cf. A025586, A033496, A087260.

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[LCM[4*w, Max[fpl[4*w]]], {w, 1, 256}]

A087258 a(n) = gcd(n, A025586(n)), greatest common divisor of n and largest value in 3x+1 iteration list started at n.

Original entry on oeis.org

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

Offset: 1

Labos Elemer, Sep 09 2003

nonn

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

Cf. A006370, A025586, A033496, A087259, A087260, A087262.

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}]

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
A087258(n) = gcd(n,A025586(n)); \\ Antti Karttunen, Dec 05 2018

cp's OEIS Frontend

A087261 a(n) = lcm(4n, A025586(4n)), least common multiple of 4n and the largest value in 3x+1 iteration list started at 4n.

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