A023996 - OEIS

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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, 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

(list; graph; refs; listen; history; text; internal format)

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

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