A154234 -id:A154234 - cp's OEIS frontend

A174428 Triangle read by rows: R(n,k) = sigma(n) mod k, where sigma(.) is the sum of divisors.

0, 0, 1, 0, 0, 1, 0, 1, 1, 3, 0, 0, 0, 2, 1, 0, 0, 0, 0, 2, 0, 0, 0, 2, 0, 3, 2, 1, 0, 1, 0, 3, 0, 3, 1, 7, 0, 1, 1, 1, 3, 1, 6, 5, 4, 0, 0, 0, 2, 3, 0, 4, 2, 0, 8, 0, 0, 0, 0, 2, 0, 5, 4, 3, 2, 1, 0, 0, 1, 0, 3, 4, 0, 4, 1, 8, 6, 4, 0, 0, 2, 2, 4, 2, 0, 6, 5, 4, 3, 2, 1, 0, 0, 0, 0, 4, 0, 3, 0, 6, 4, 2, 0, 11, 10

Offset: 1

Juri-Stepan Gerasimov, Nov 28 2010

			The triangle starts in row n=1 with columns 1<=k<=n as:
  0;
  0,1;
  0,0,1;
  0,1,1,3;
  0,0,0,2,1;
  0,0,0,0,2,0;
  0,0,2,0,3,2,1;

Cf. A000203, A154234.

Flatten[Table[Mod[DivisorSigma[1,n],k],{n,20},{k,n}]] (* Harvey P. Dale, Apr 17 2014 *)

A177338 Triangle read by rows: T(n,k) = 2^(n-tau(k)) mod n, where tau(.) is the number of divisors of its argument.

Original entry on oeis.org

0, 0, 1, 1, 2, 2, 0, 0, 0, 2, 1, 3, 3, 4, 3, 2, 4, 4, 2, 4, 4, 1, 4, 4, 2, 4, 1, 4, 0, 0, 0, 0, 0, 0, 0, 0, 4, 2, 2, 1, 2, 5, 2, 5, 1, 2, 6, 6, 8, 6, 4, 6, 4, 8, 4, 1, 6, 6, 3, 6, 7, 6, 7, 3, 7, 6, 8, 4, 4, 8, 4, 4, 4, 4, 8, 4, 4, 4, 1, 7, 7, 10, 7, 5, 7, 5, 10, 5, 7, 11, 7, 2, 8, 8, 4, 8, 2, 8

Offset: 1

Juri-Stepan Gerasimov, Dec 10 2010

			Triangle begins in row n=1 with columns 1 <= k <= n:
  0;
  0, 1;
  1, 2, 2;
  0, 0, 0, 2;
  1, 3, 3, 4, 3;
  2, 4, 4, 2, 4, 4;

Cf. A000005, A000079, A062173, A154234, A174875.

trg(nn) = {for (n= 1, nn, for (k = 1, n, print1(2^(n - numdiv(k)) % n, ", ");); print(););} \\ Michel Marcus, Sep 11 2013

cp's OEIS Frontend

A174428 Triangle read by rows: R(n,k) = sigma(n) mod k, where sigma(.) is the sum of divisors.

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