A248571 Number of connected irreducible digital images of n points up to homotopy equivalence.

1, 0, 0, 0, 1, 1, 3, 28, 547

Offset

1,7

Comments

"Irreducible" means not homotopy equivalent to any digital image of fewer points. The terms are nonzero for all n>4, and are believed to be strictly increasing for n>6.

Links

Table of n, a(n) for n=1..9.

J. Haarmann, M. Murphy, C. Peters, and P. C. Staecker, Homotopy equivalence of finite digital images, arXiv:1408.2584 [math.GN], 2014.

P. C. Staecker, Some enumerations of binary digital images, arXiv:1502.06236 [math.CO], 2015.

Crossrefs

Sequence in context: A192559 A161971 A156315 * A062497 A367391 A056066

Adjacent sequences: A248568 A248569 A248570 * A248572 A248573 A248574

Keyword

nonn,more,hard

Author

P. Christopher Staecker, Oct 13 2014

Extensions

a(8)-a(9) from P. Christopher Staecker, Feb 24 2015

Status

approved