A333281 Column 2 of triangle in A288180.

13, 37, 121, 265, 587, 1019, 1797, 2823, 4369, 6257, 9001, 12289, 16775, 21905, 28383, 35901, 45463, 56119, 69351, 84167, 101687, 120869, 143777, 168873, 198191, 229771, 266015, 305379, 350673, 399035, 454243, 513619, 579787, 649899, 727927, 810907, 903581

Offset

1,1

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.

Sequence in context: A155259 A155308 A166101 * A195543 A262755 A155300

Adjacent sequences: A333278 A333279 A333280 * A333282 A333283 A333284

Keyword

nonn

Author

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

Extensions

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

Status

approved