Series for second parallel moment of square lattice (eventually changes sign).

Terms

a(0) =0a(1) =2a(2) =16a(3) =68a(4) =220a(5) =608a(6) =1520a(7) =3526a(8) =7756a(9) =16302a(10) =33172a(11) =65378a(12) =126224a(13) =237600a(14) =441776a(15) =802820a(16) =1451932a(17) =2563356a(18) =4544304a(19) =7818078a(20) =13684784a(21) =22938278a(22) =39986208a(23) =64996080a(24) =114280984a(25) =177912196a(26) =322438072a(27) =467942962a(28) =909533348a(29) =1162410740