4,3

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.

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

Cf. A006627, A002854.

Sequence in context: A137279 A167350 A156457 this_sequence A076021 A078630 A057402

Adjacent sequences: A085615 A085616 A085617 this_sequence A085619 A085620 A085621

nonn

N. J. A. Sloane (njas(AT)research.att.com), Jul 11 2003