A027607 Number of non-well-founded sets or hypersets (sets that can contain themselves) of level n (representable by graphs with n nodes).

2, 2, 16, 504, 52944, 17294924, 17347940328

Offset

1,1

Links

Table of n, a(n) for n=1..7.

A. Casagrande, C. Piazza, A. Policriti, Is hyper-extensionality preservable under deletions of graph elements?, Preprint 2015.

Christopher Tubbs et al., GitHub Hypersets Project for generating integers in the sequence.

Crossrefs

Sequence in context: A012520 A012323 A009804 * A100680 A002567 A238289

Adjacent sequences: A027604 A027605 A027606 * A027608 A027609 A027610

Keyword

nonn,hard,more

Author

Elaine Milito (emilito(AT)bird.wcupa.edu)

Extensions

a(6)-a(7) from Christopher Tubbs, Oct 19 2013

Status

approved