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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.
1
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
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: A266344 A376917 A334944 * A193510 A353337 A351907
KEYWORD
nonn,tabl,easy
AUTHOR
STATUS
approved