Partial sums of squares of A000975.

Terms

a(0) =0a(1) =1a(2) =5a(3) =30a(4) =130a(5) =571a(6) =2335a(7) =9560a(8) =38460a(9) =154741a(10) =619865a(11) =2483090a(12) =9935990a(13) =39758511a(14) =159048595a(15) =636252620a(16) =2545068720a(17) =10180507881a(18) =40722264525a(19) =162889990150a(20) =651560892650