A348461 Size of largest bipartite biregular Moore graph of diameter 4 and degrees n and n.

8, 30, 80, 170, 312

Offset: 2

Author

N. J. A. Sloane, Oct 31 2021

Keywords

• nonn
• more

Comments

a(7) >= 516, a(8) = 800, a(9) = 1170, a(10) = 1640.

Links

• G. Araujo-Pardo, C. Dalfó, M. Á. Fiol and N. López, Bipartite biregular Moore graphs, arXiv:2103.11443 [math.CO], 2021.
• G. Araujo-Pardo, C. Dalfó, M. Á. Fiol and N. López, Bipartite biregular Moore graphs, Discrete Math., 334 (2021), # 112582.

Crossrefs

Cf. A027444, A053698, A348462, A348463.

Formula

Empirical observation: For the terms a(2)-a(6) and a(8)-a(10) a(n) = 2*(A027444(n-1) + 1). It is unknown whether this is also valid for n = 7 and n > 10. - Hugo Pfoertner, Oct 31 2021

Is this the same as 2*A053698(n-1)? If not, where is the first place these sequences differ? - Omar E. Pol, Oct 31 2021

a(n) <= 2*A053698(n-1) (the Moore bound). - Pontus von Brömssen, Oct 31 2021