login
The OEIS Foundation is supported by donations from users of the OEIS and by a grant from the Simons Foundation.

 

Logo


Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A085618 Number of self-complementary 2-graphs with n nodes. 2
1, 1, 4, 0, 19, 10 (list; graph; refs; listen; history; text; internal format)
OFFSET

4,3

COMMENTS

Sozański (1980, p. 141) says: "Note that formula (20) also gives the number of isomorphism classes of self-complementary p-point two-graphs." Formula (20) apparently refers to sequence A263626 (according to the references there). Is this sequence the same as A263626? (This would mean a(n) = 0 for 3 == n mod 4.) - Petros Hadjicostas, Feb 27 2021

LINKS

Table of n, a(n) for n=4..9.

F. C. Bussemaker, R. A. Mathon and J. J. Seidel, Tables of two-graphs, T.H.-Report 79-WSK-05, Technological University Eindhoven, Dept. Mathematics, 1979; also pp. 71-112 of "Combinatorics and Graph Theory (Calcutta, 1980)", Lect. Notes Math. 885, 1981.

F. C. Bussemaker, R. A. Mathon and J. J. Seidel, Tables of two-graphs, T.H.-Report 79-WSK-05, Technological University Eindhoven, Dept. Mathematics, 1979; also pp. 71-112 of "Combinatorics and Graph Theory (Calcutta, 1980)", Lect. Notes Math. 885, 1981.

Tadeusz Sozański, Enumeration of weak isomorphism classes of signed graphs, J. Graph Theory 4 (1980), no. 2, 127-144.

CROSSREFS

Cf. A002854, A006627, A263626.

Sequence in context: A156457 A058348 A184946 * A263626 A076021 A282579

Adjacent sequences:  A085615 A085616 A085617 * A085619 A085620 A085621

KEYWORD

nonn,more

AUTHOR

N. J. A. Sloane, Jul 11 2003

STATUS

approved

Lookup | Welcome | Wiki | Register | Music | Plot 2 | Demos | Index | Browse | More | WebCam
Contribute new seq. or comment | Format | Style Sheet | Transforms | Superseeker | Recent
The OEIS Community | Maintained by The OEIS Foundation Inc.

License Agreements, Terms of Use, Privacy Policy. .

Last modified June 15 04:47 EDT 2021. Contains 345043 sequences. (Running on oeis4.)