Theta series of square lattice (or number of ways of writing n as a sum of 2 squares).
1, 4, 4, 0, 4, 8, 0, 0, 4, 4, 8, 0, 0, 8, 0, 0, 4, 8, 4, 0, 8, 0, 0, 0, 0, 12, 8, 0, 0, 8, 0, 0, 4, 0
1 seqfan posts
Thu Mar 24 16:33:46 CET 2011 [seqfan] Re: sigma(4n+1) mod 4 and partitions