A213451 Number of fixed triangular strip polyedges with n edges. (Formerly N1209)

3, 15, 69, 309, 1365, 5973, 25941, 112065, 482067, 2066583, 8834469, 37677603, 160367343

Offset

1,1

References

N. J. A. Sloane, A Handbook of Integer Sequences, Academic Press, 1973 (includes this sequence).

Links

Table of n, a(n) for n=1..13.

C. Domb, On the theory of cooperative phenomena in crystals, Advances in Phys., 9 (1960), 149-361. See page 354.

Formula

Apparently, a(n) = A001334(n)/2 for n >= 1. It needs to be clarified whether the objects described by this sequence are equivalent to the self-avoiding walks on the hexagonal lattice together with a restriction on their orientation. - Hugo Pfoertner, Jul 24 2021

Crossrefs

Cf. A001334, A151540, A151541.

Sequence in context: A325586 A304276 A217451 * A224749 A122558 A110211

Adjacent sequences: A213448 A213449 A213450 * A213452 A213453 A213454

Keyword

nonn,more

Author

N. J. A. Sloane, Jun 11 2012

Extensions

Better description and more terms from Joseph Myers, Jun 12 2012

Status

approved