A174875 Triangle read by rows: T(n,k) = sigma(n) mod tau(k), where sigma(.) is the sum of divisors and tau(.) is the number of divisors.

0, 0, 1, 0, 0, 0, 0, 1, 1, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 2, 0, 0, 0, 0, 1, 1, 0, 1, 3, 1, 3, 0, 1, 1, 1, 1, 1, 1, 1, 1, 0, 0, 0, 0, 0, 2, 0, 2, 0, 2, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 1, 0, 0, 4, 0, 0, 0, 2, 0, 2, 0, 2, 2, 2, 0, 2, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0

Offset: 1

Author

Juri-Stepan Gerasimov, Dec 02 2010

Keywords

• nonn
• tabl
• easy

Examples

			The triangle starts at row n=1 with columns k = 1..n:
  0;
  0,1;
  0,0,0;
  0,1,1,1;
  0,0,0,0,0;
  0,0,0,0,0,0;
  0,0,0,2,0,0,0;
  0,1,1,0,1,3,1,3;
  0,1,1,1,1,1,1,1,1;
  0,0,0,0,0,2,0,2,0,2;
  0,0,0,0,0,0,0,0,0,0,0;
		

Crossrefs

Cf. A000005, A000203, A054025 (right diagonal).

Programs

Mathematica

Array[Mod[DivisorSigma[1, #], DivisorSigma[0, Range[#]]] &, 15] (* Paolo Xausa, Jun 28 2024 *)