1,6
Eric Weisstein's World of Mathematics, Critical Nonplanar Graph
Sequence in context: A068775 A073955 A188332 * A117083 A007987 A092397
Adjacent sequences: A158919 A158920 A158921 * A158923 A158924 A158925
nonn,more
E. W. Weisstein (eric(AT)weisstein.com), Mar 31, 2009