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A369997
Irregular triangle read by rows: T(n,k) is the number of connected induced k-vertex subgraphs, up to isomorphism, of the hypercube graph of dimension n >= 0, 1 <= k <= 2^n.
4
1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 3, 2, 3, 1, 1, 1, 1, 1, 3, 4, 9, 15, 31, 35, 40, 24, 18, 6, 4, 1, 1
OFFSET
0,11
COMMENTS
In A369605, two isomorphic subgraphs may both be counted, namely if there is no automorphism of the hypercube graph that takes one to the other. The first difference is T(4,5) = 4 < A369605(4,5) = 5. The path with 5 vertices is an induced subgraph of the 4-dimensional hypercube in two inequivalent ways: one that is contained in a 3-dimensional subcube and one that is not.
EXAMPLE
Triangle begins:
1;
1, 1;
1, 1, 1, 1;
1, 1, 1, 3, 2, 3, 1, 1;
1, 1, 1, 3, 4, 9, 15, 31, 35, 40, 24, 18, 6, 4, 1, 1;
...
CROSSREFS
Cf. A369605 (up to automorphisms of the hypercube), A369995 (not necessarily connected subgraphs), A369998 (row sums), A369999.
Sequence in context: A103497 A191390 A309698 * A369605 A085747 A106693
KEYWORD
nonn,tabf,more
AUTHOR
STATUS
approved