A333280 Column 2 of triangle in A333278.

28, 92, 296, 652, 1408, 2470, 4312, 6774, 10428, 14992, 21492, 29328, 39876, 52184, 67616, 85588, 108192, 133674, 164992, 200158, 241560, 287428, 341768, 401472, 470764, 546230, 632404, 726170, 833420, 948550, 1079204, 1220054, 1376552, 1543742, 1729000

Offset: 1

Author

Scott R. Shannon and N. J. A. Sloane, Mar 15 2020

Keywords

• nonn

Comments

For the graphs defined in A331452 and A288187 only the counts for graphs that are one square wide have formulas for regions, edges, and vertices (see A306302, A331757, A331755). For width 2 there are six such sequences (A331766, A331765, A331763; A333279, A333280, A333281). It would be nice to have a formula for any one of them.

See A333279 for illustrations.

Links

• Lars Blomberg, Table of n, a(n) for n = 1..200
• Hugo Pfoertner, Illustrations of Chamber Complexes up to 5 X 5.

Crossrefs

Cf. A331452, A288187; A331766, A331765, A331763; A333279, A333280, A333281.

Extensions

a(10) and beyond from Lars Blomberg, May 23 2021