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A294224
Triangle read by rows: T(n,k) is the number of graphs with n vertices and skewness k (n >= 1 and k >= 0).
0
1, 2, 4, 11, 33, 1, 142, 12, 1, 1, 822, 169, 39, 10, 2, 1, 1, 6966, 3580, 1241, 378, 120, 36, 16, 5, 2, 1, 1, 79853, 92850, 59115, 26667, 10344, 3666, 1381, 483, 184, 75, 30, 11, 5, 2, 1, 1
OFFSET
1,2
COMMENTS
The sum of the n-th row is equal to A000088(n).
Length of the n-th row kmax(n) is A000124(n-4) for n > 3 (conjectured).
LINKS
Eric Weisstein's World of Mathematics, Graph Skewness
FORMULA
T(n,0) = A005470(n).
T(n,kmax(n)) = 1 for n > 4.
T(n,kmax(n)-1) = 1 for n > 5.
EXAMPLE
Triangle begins:
1
2
4
11
33,1
142,12,1,1
822,169,39,10,2,1,1
6966,3580,1241,378,120,36,16,5,2,1,1
CROSSREFS
Cf. A000088 (number of simple graphs on n nodes).
Cf. A005470 (number of planar simple graphs on n nodes).
Cf. A000124 (central polygonal numbers).
Sequence in context: A123404 A178925 A298445 * A296270 A123439 A026164
KEYWORD
nonn,tabf,more
AUTHOR
Eric W. Weisstein, Oct 25 2017
STATUS
approved