A087976 a(n) = A001221(A025586(n)), the number of distinct prime-factors of maximal term in 3x+1 iteration list started at n.

0, 1, 1, 1, 1, 1, 2, 1, 2, 1, 2, 1, 2, 2, 2, 1, 2, 2, 2, 2, 1, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 1, 2, 2, 2, 2, 2, 2, 2, 2, 2, 1, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 1, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 3, 2, 2, 2, 2, 2, 2, 2, 2, 3, 1, 2, 2, 2, 2, 2, 2, 2, 3, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2

Offset

1,7

Links

G. C. Greubel, Table of n, a(n) for n = 1..1000

Mathematica

Collatz[a0_Integer, maxits_: 1000] := NestWhileList[If[EvenQ[#], #/2, 3 # + 1] &, a0, Unequal[#, 1, -1, -10, -34] &, 1, maxits]; (*Collatz[n] function definition by Eric Weisstein*) A025586[m_] :=
Flatten[Table[Take[Sort[Collatz[n], Greater], 1], {n, m}]];
PrimeNu[A025586[100]] (* G. C. Greubel, Apr 24 2017 *)

Crossrefs

Cf. A001221, A025586, A087974, A087975.

Sequence in context: A359944 A359308 A107459 * A227903 A353567 A117277

Adjacent sequences: A087973 A087974 A087975 * A087977 A087978 A087979

Keyword

nonn

Author

Labos Elemer, Sep 25 2003

Status

approved