A023996 Triangle of numbers T(n,k), where T(n,k) is the number of sets S = {a_1, a_2, ..., a_k}, with 1 < a_i < a_j <= n such that no a_j divides the product of all the others.

1, 1, 1, 1, 2, 1, 1, 3, 2, 1, 4, 5, 2, 1, 5, 7, 3, 1, 6, 12, 10, 3, 1, 7, 16, 15, 5, 1, 8, 22, 24, 9, 1, 9, 28, 34, 14, 1, 10, 37, 62, 48, 14, 1, 11, 43, 74, 58, 17, 1, 12, 54, 117, 132, 75, 17, 1, 13, 64, 151, 182, 108, 25, 1, 14, 75, 184, 224, 132, 30, 1, 15, 86

Offset

0,5

Links

Sean A. Irvine, Table of n, a(n) for n = 0..586 (rows 0..55 flattened)

Sean A. Irvine, Java program (github)

Example

From Sean A. Irvine, Jun 17 2019: (Start)
  1;
  1,  1;
  1,  2,  1;
  1,  3,  2;
  1,  4,  5,  2;
  1,  5,  7,  3;
  1,  6, 12, 10,  3;
  ... (End)

Crossrefs

Cf. A023995.

Sequence in context: A266715 A089177 A348445 * A307998 A355147 A049998

Adjacent sequences: A023993 A023994 A023995 * A023997 A023998 A023999

Keyword

tabf,nonn

Author

Lionel Levine (levine(AT)ultranet.com)

Status

approved