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

Author

Lionel Levine (levine(AT)ultranet.com)

Keywords

• nonn

Examples

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

Links

• Sean A. Irvine, Java program (github)

Crossrefs

Cf. A038199.

Extensions

More terms from Sean A. Irvine, Jun 17 2019