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

1,25

Links

Table of n, a(n) for n=1..105.

Example

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;

Mathematica

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

Crossrefs

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

Sequence in context: A319995 A266344 A334944 * A193510 A353337 A351907

Adjacent sequences: A174872 A174873 A174874 * A174876 A174877 A174878

Keyword

nonn,tabl,easy

Author

Juri-Stepan Gerasimov, Dec 02 2010

Status

approved