A077027 Number of simple integral graphs on n nodes.

1, 2, 3, 6, 10, 20, 33, 71, 121, 269, 492

Offset

1,2

Comments

Generated at the suggestion of Ed Pegg Jr.

Links

Table of n, a(n) for n=1..11.

Eric Weisstein's World of Mathematics, Integral Graph

Formula

Euler transform of A064731. - Eric M. Schmidt, Mar 23 2015

a(n) = A287154(n) + A064731(n).

Crossrefs

Cf. A064731 (number of simple connected integral graphs).

Cf. A287154 (number of simple disconnected integral graphs).

Cf. A363065 (number of Laplacian integral graphs).

Sequence in context: A214002 A305889 A135452 * A030436 A030227 A180272

Adjacent sequences: A077024 A077025 A077026 * A077028 A077029 A077030

Keyword

nonn,more

Author

Eric W. Weisstein, Oct 18 2002

Extensions

a(1) corrected and a(10)-a(11) added (using A064731) by Eric M. Schmidt, Mar 23 2015

Status

approved