A348463 Size of largest bipartite biregular Moore graph of diameter 6 and degrees n and n.

12, 126, 728, 2730, 7812

Offset: 2

Author

N. J. A. Sloane, Oct 31 2021

Keywords

• nonn
• more

Comments

18660 <= a(7) <= 18662, a(8) = 39216, a(9) = 74898, a(10) = 132860.

Table 3 from these references gives the size of the largest bipartite biregular Moore graph of diameter 3 and degrees n and n, and appears to match 2*A002061.

Links

• G. Araujo-Pardo, C. Dalfó, M. Á. Fiol and N. López, Bipartite biregular Moore graphs, arXiv:2103.11443 [math.CO], 2021. See Table 2.
• G. Araujo-Pardo, C. Dalfó, M. Á. Fiol and N. López, Bipartite biregular Moore graphs, Discrete Math., 334 (2021), # 112582. See Table 3.

Crossrefs

Cf. A002061, A053700, A152031, A348461, A348462.

Formula

Empirical observation: a(n) = 2*(A152031(n-1) + 1) matches terms a(2)-a(6) and a(8)-a(10). - Hugo Pfoertner, Oct 31 2021

a(n) <= 2*A053700(n-1) = 2*(A152031(n-1) + 1) (the Moore bound). - Pontus von Brömssen, Oct 31 2021