A121998 Table, n-th row gives numbers between 1 and n that have a common factor with n.

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

Offset

2,1

Comments

Row n contains numbers m <= n such that gcd(m,n) > 1, i.e., numbers m in the cototient of n. - Michael De Vlieger, Mar 13 2018

Links

Michael De Vlieger, Table of n, a(n) for n = 2..12949 (rows 2 <= n <= 256).

Example

2;
3;
2,4;
5;
2,3,4,6;
7;
...

Mathematica

Table[Select[Range@ n, ! CoprimeQ[#, n] &], {n, 20}] // Flatten (* Michael De Vlieger, Mar 13 2018 *)

Crossrefs

Cf. A051953 (row lengths), A038566, A081520, A133995 (nondivisors in the cototient of n).

Sequence in context: A326764 A071495 A071515 * A120499 A027749 A226208

Adjacent sequences: A121995 A121996 A121997 * A121999 A122000 A122001

Keyword

nonn,tabf

Author

Franklin T. Adams-Watters, Sep 11 2006

Status

approved