A077661 Triangle read by rows in which the n-th row contains n smallest numbers not coprime to n; except first row = {1}.

1, 2, 4, 3, 6, 9, 2, 4, 6, 8, 5, 10, 15, 20, 25, 2, 3, 4, 6, 8, 9, 7, 14, 21, 28, 35, 42, 49, 2, 4, 6, 8, 10, 12, 14, 16, 3, 6, 9, 12, 15, 18, 21, 24, 27, 2, 4, 5, 6, 8, 10, 12, 14, 15, 16, 11, 22, 33, 44, 55, 66, 77, 88, 99, 110, 121, 2, 3, 4, 6, 8, 9, 10, 12, 14, 15, 16, 18

Offset: 1

Author

Amarnath Murthy, Nov 14 2002

Keywords

• nonn
• look
• tabl

Examples

			Triangle begins as:
  1;
  2,  4;
  3,  6,  9;
  2,  4,  6,  8;
  5, 10, 15, 20, 25;
  2,  3,  4,  6,  8,  9;
  7, 14, 21, 28, 35, 42, 49;
  ...
		

Links

• Alois P. Heinz, Rows n = 1..200, flattened

Crossrefs

Cf. A077662, A077663.

Programs

Mathematica

Join[{1},Table[Take[Select[Range[n^2],GCD[#,n]!=1 &],n],{n,2,13}]]//Flatten (* Stefano Spezia, Jan 10 2025 *)

Extensions

More terms from Sascha Kurz, Jan 27 2003