Search: id:A077550 Results 1-1 of 1 results found. %I A077550 %S A077550 1,1,2,3,9,21,54,131 %N A077550 Number of nonisomorphic ways a river (or undirected line) can cross two perpendicular roads n times (orbits of A076875 under symmetry group of order 8). %C A077550 There is no constraint on touching any particular sector. %Y A077550 Cf. A076875 (total number of solutions), A076906, A076907 (if line is directed) %Y A077550 Sequence in context: A015951 A101531 A099607 this_sequence A056780 A141505 A111360 %Y A077550 Adjacent sequences: A077547 A077548 A077549 this_sequence A077551 A077552 A077553 %K A077550 nonn %O A077550 0,3 %A A077550 N. J. A. Sloane (njas(AT)research.att.com) and Jon Wild (wild(AT)music.mcgill.ca), Aug 25 2003 Search completed in 0.001 seconds