%I #17 Jul 15 2023 06:35:23
%S 1,2,4,6,8,12,21,30,38,48,63,91,145,222,390,558,712,892,1142,1456,
%T 1936,2464,3270,4792,7690,11854,18757,28733,47355,73632,130315,186998,
%U 239552,300347,388902,492078,643230,816210,1057438,1354293,1804608,2338124,3111812
%N Number of subsets S of {A007931(1), A007931(2), ..., A007931(n)} with the property that no element of S is a substring of any other.
%C These subsets form an independence system, also called an abstract simplicial complex.
%H Wikipedia, <a href="https://en.wikipedia.org/wiki/Abstract_simplicial_complex">Abstract simplicial complex</a>
%H Wikipedia, <a href="https://en.wikipedia.org/wiki/Independence_system">Independence system</a>
%e For n = 5 the a(5) = 12 independent sets of {A007931(1), A007931(2), ..., A007931(5)} = {1, 2, 11, 12, 21} are:
%e 1) {};
%e 2) {1};
%e 3) {2};
%e 4) {2, 1};
%e 5) {11};
%e 6) {11, 2};
%e 7) {12};
%e 8) {12, 11};
%e 9) {21};
%e 10) {21, 11};
%e 11) {21, 12}; and
%e 12) {21, 12, 11}.
%e In each of these twelve sets, no string is a substring of any other. In particular, {12, 11, 2} is not an independent set because 2 is a substring of 12.
%Y Cf. A007931.
%K nonn,base
%O 0,2
%A _Peter Kagey_, May 19 2023
%E More terms from _Pontus von Brömssen_, Jul 15 2023