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a(n) is the number of inequivalent binary delta-matroids on a ground set of size n.
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%I #15 Feb 14 2024 14:27:44

%S 5,13,40,141

%N a(n) is the number of inequivalent binary delta-matroids on a ground set of size n.

%H Daniel Yuschak, <a href="https://arxiv.org/abs/2208.13258">Delta-matroids with twist monomials</a>, arXiv:2208.13258 [math.CO], 2022-2023.

%H Daniel Yuschak, <a href="https://doi.org/10.1016/j.ejc.2024.103925">Delta-matroids whose twist polynomials are monomials</a>, European Journal of Combinatorics 118, 103925 (2024).

%F a(n) <= A006125(n+1).

%Y Cf. A006125, A370096.

%K nonn,more

%O 2,1

%A _Stefano Spezia_, Feb 09 2024