O.g.f.: exp( Sum_{n>=1} -(sigma(2*n^2) - sigma(n^2)) * (-x)^n/n ).

Terms

a(0) =1a(1) =2a(2) =-2a(3) =2a(4) =10a(5) =-10a(6) =6a(7) =10a(8) =-22a(9) =58a(10) =-58a(11) =10a(12) =114a(13) =-210a(14) =270a(15) =-242a(16) =74a(17) =382a(18) =-930a(19) =1474a(20) =-1542a(21) =1010a(22) =446a(23) =-2798a(24) =5682a(25) =-7718a(26) =8030a(27) =-5182a(28) =-998a(29) =11126