A174063 Triangular array (read by rows) containing the least n integers < 2n such that no integer divides another.

1, 2, 3, 2, 3, 5, 2, 3, 5, 7, 4, 5, 6, 7, 9, 4, 5, 6, 7, 9, 11, 4, 5, 6, 7, 9, 11, 13, 4, 6, 7, 9, 10, 11, 13, 15, 4, 6, 7, 9, 10, 11, 13, 15, 17, 4, 6, 7, 9, 10, 11, 13, 15, 17, 19, 4, 6, 9, 10, 11, 13, 14, 15, 17, 19, 21, 4, 6, 9, 10, 11, 13, 14, 15, 17, 19, 21, 23, 4, 6, 9, 10, 11, 13, 14

Offset: 1

Author

David Brown, Mar 07 2010

Keywords

• nonn
• tabl

Comments

The first number on each row is 2^k, where k is the greatest integer such that (3^k)/2 < n.

Examples

			1;
2, 3;
2, 3, 5;
2, 3, 5, 7;
4, 5, 6, 7, 9;
4, 5, 6, 7, 9, 11;
4, 5, 6, 7, 9, 11, 13;
4, 6, 7, 9, 10, 11, 13, 15;
		

Crossrefs

Cf. A174062, A174094.

Programs

Mathematica

noneDivQ[L_] := NoneTrue[Subsets[L, {2}], Divisible[#[[2]], #[[1]]]&];
k1[n_] := For[k = Log[3, 2n]//Ceiling, True, k--, If[(3^k)/2Jean-François Alcover, Sep 25 2020 *)

Extensions

Definition corrected by David Brown, Mar 20 2010