A294224 Triangle read by rows: T(n,k) is the number of graphs with n vertices and skewness k (n >= 1 and k >= 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

Table of n, a(n) for n=1..44.

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

Adjacent sequences: A294221 A294222 A294223 * A294225 A294226 A294227

Keyword

nonn,tabf,more

Author

Eric W. Weisstein, Oct 25 2017

Status

approved