Series for second perpendicular moment of square lattice.

Terms

a(0) =0a(1) =2a(2) =8a(3) =24a(4) =60a(5) =136a(6) =288a(7) =582a(8) =1132a(9) =2138a(10) =3940a(11) =7114a(12) =12632a(13) =22080a(14) =38160a(15) =65056a(16) =110172a(17) =184032a(18) =306968a(19) =503650a(20) =831408a(21) =1340338a(22) =2201840a(23) =3479116a(24) =5733312a(25) =8814468a(26) =14772040a(27) =21734370a(28) =37997724a(29) =51650456