A023995 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, 2, 4, 6, 12, 16, 32, 44, 64, 86, 172, 204, 408, 544, 660, 860, 1720, 2080, 4160, 4800, 5792, 7784, 15568, 17440, 23648, 31616, 40976, 46584, 93168, 102768, 205536, 261600, 316160, 426304, 479616, 524112, 1048224, 1407856, 1699568, 1848384, 3696768, 4049376, 8098752, 9292544

Offset

1,2

Links

Table of n, a(n) for n=1..44.

Sean A. Irvine, Java program (github)

Example

f(4)=6: {}, {2}, {3}, {4}, {2,3}, {3,4}.

Crossrefs

Cf. A038199.

Sequence in context: A233968 A120453 A326438 * A018189 A239954 A332640

Adjacent sequences: A023992 A023993 A023994 * A023996 A023997 A023998

Keyword

nonn

Author

Lionel Levine (levine(AT)ultranet.com)

Extensions

More terms from Sean A. Irvine, Jun 17 2019

Status

approved