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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. 3

%I #10 Jun 18 2019 03:31:55

%S 1,2,4,6,12,16,32,44,64,86,172,204,408,544,660,860,1720,2080,4160,

%T 4800,5792,7784,15568,17440,23648,31616,40976,46584,93168,102768,

%U 205536,261600,316160,426304,479616,524112,1048224,1407856,1699568,1848384,3696768,4049376,8098752,9292544

%N 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.

%H Sean A. Irvine, <a href="https://github.com/archmageirvine/joeis/blob/master/src/irvine/oeis/a023/A023995.java">Java program</a> (github)

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

%Y Cf. A038199.

%K nonn

%O 1,2

%A Lionel Levine (levine(AT)ultranet.com)

%E More terms from _Sean A. Irvine_, Jun 17 2019

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Last modified April 23 16:40 EDT 2024. Contains 371916 sequences. (Running on oeis4.)