A350035 Number of steps to reach 1 under repeated applications of the A350034 map, or -1 if 1 is never reached.

0, 1, 1, 2, 11, 1, 3, 3, 2, 12, 7, 2, 9, 4, 12, 4, 6, 2, 6, 13, 4, 8, 16, 3, 6, 10, 3, 5, 13, 12, 12, 5, 8, 7, 12, 2, 14, 7, 10, 14, 9, 4, 4, 9, 13, 17, 21, 4, 11, 7, 7, 11, 19, 3, 19, 6, 7, 14, 18, 13, 9, 13, 5, 6, 13, 8, 8, 8, 17, 13, 20, 3, 11, 15, 7, 8, 15, 10, 10, 15, 4, 10, 15, 5, 22, 5

Offset

1,4

Links

Winston de Greef, Table of n, a(n) for n = 1..10000

Example

5 -> 26 -> 13 -> 66 -> 11 -> 56 -> 28 -> 14 -> 7 -> 36 -> 6 -> 1. Thus a(5) = 11.

Maple

a:= proc(n) option remember; `if`(n=1, 0, 1+
      a((g-> `if`(g>1, n/g, 5*n+1))(igcd(n, 6))))
    end:
seq(a(n), n=1..100);  # Alois P. Heinz, Jan 19 2022

Mathematica

f[n_]:=If[GCD[n, 6]>1, n/GCD[n, 6], 5*n+1]; Table[f[n], {n, 0, 100}];
S[n_]:=S[n]=Which[n==1, 0, f[n]==1, 1, True, 1+S[f[n]]];
Table[S[n], {n, 1, 86}]

Prog

(PARI)
A350034(n) = my(g = gcd(n, 6)); if (g>1, n/g, 5*n+1);
a(n)=my(r=0); while(n != 1, n = A350034(n); r+=1); r \\ Winston de Greef, Oct 02 2023

Crossrefs

Cf. A350034, A006370, A089128, A006577, A133420.

Sequence in context: A348942 A057213 A326042 * A353877 A250221 A365610

Adjacent sequences: A350032 A350033 A350034 * A350036 A350037 A350038

Keyword

nonn

Author

José María Grau Ribas, Jan 19 2022

Status

approved