A128941 Cardinality of the free modular lattice generated by two elements and a chain of length n.
4, 28, 138, 629, 2784, 12134, 52366, 224404, 956514, 4060036, 17175130, 72454073, 304941384, 1280898302, 5371301502, 22491017756, 94055344242, 392888085098, 1639534704630, 6835739258996, 28477594607346, 118551827347574
Offset: 0
Keywords
Examples
When n = 0, the lattice consists of the two elements, their meet and their join, so a(0) = 4. When n = 1, we get the free modular lattice generated by three elements, so a(1) = 28.
References
- G. Birkoff, Lattice Theory, American Mathematical Society, third edition (1967), pp. 63-64 [for the case n = 1].
Links
- M. P. Schützenberger, Construction du treillis modulaire engendré par deux éléments et une chaine finie discrète, Comptes Rendus de lAcad. Sci. Paris, vol. 235 (1952), pp. 926-928.
- K. Takeuchi, On free modular lattices II, Tohoku Mathematical Journal (2), vol. 11 (1959), pp. 1-12 [for the case n = 2].
Crossrefs
Cf. A137400.
Extensions
More terms from Vladeta Jovovic, Feb 05 2010
Comments