A283755 - OEIS

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A283755

Irregular triangular array read by rows: T(n,k) = number of non-isomorphic unlabeled connected graphs with loops on n nodes and with k edges.

1, 1, 1, 1, 1, 1, 3, 3, 2, 1, 2, 6, 11, 13, 10, 5, 2, 1, 3, 14, 35, 61, 75, 68, 49, 28, 13, 5, 2, 1, 6, 33, 112, 262, 463, 625, 684, 620, 468, 301, 170, 82, 35, 14, 5, 2, 1, 11, 81, 347, 1059, 2458, 4565, 7018, 9122, 10186, 9878, 8366, 6219, 4085, 2377, 1232, 582, 251, 98, 37, 14, 5, 2, 1, 23, 204, 1085, 4091, 12014, 28779, 58162, 101315, 154484, 208321, 250120, 268649, 258994

(list; graph; refs; listen; history; text; internal format)

OFFSET

1,7

COMMENTS

The range for the subindex k is from n-1 to n(n+1)/2.

REFERENCES

E. Palmer and F. Harary, Graphical Enumeration, Academic Press, 1973.

LINKS

Table of n, a(n) for n=1..83.

Marko R. Riedel, Number of distinct connected digraphs

Marko Riedel, Maple code for A070166 and A283755.

FORMULA