A186808 - OEIS

A186808

Numbers n such that there are a prime number of unlabeled distributive lattices with n elements.

4, 5, 6, 10, 12, 13, 18, 21, 23, 26

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OFFSET

1,1

COMMENTS

A lattice which satisfies the identities:

(x^y)V(x^z) = x^(yVz);

(xVy)^(xVz) = xV(y^z)

is said to be distributive.

REFERENCES

Gratzer, G. Lattice Theory: First Concepts and Distributive Lattices. San Francisco, CA: W. H. Freeman, pp. 35-36, 1971.

LINKS

FORMULA

{k: A006982(k) is in A000040}.

EXAMPLE

a(10) = 26 because there are 711811 unlabeled distributive lattices with 26 elements, and 711811 is a prime number.

CROSSREFS

KEYWORD

nonn

AUTHOR

STATUS

approved