Annual Appeal: Please make a donation (tax deductible in USA) to keep the OEIS running. Over 5000 articles have referenced us, often saying "we discovered this result with the help of the OEIS".
Table of n, a(n) for n=1..70.
John S. Rutherford, Sublattice enumeration. IV. Equivalence classes of plane sublattices by parent Patterson symmetry and colour lattice group type, Acta Cryst. (2009). A65, 156-163. [See Table 2.]
a(n) = (A000203 + A145390)/2. [Rutherford] - N. J. A. Sloane, Mar 13 2009
Sequence in context: A085180 A114750 A234923 * A057756 A160051 A082746
Adjacent sequences: A145388 A145389 A145390 * A145392 A145393 A145394
N. J. A. Sloane, Feb 23 2009