First differences of sigma(n).

Terms

a(0) =2a(1) =1a(2) =3a(3) =-1a(4) =6a(5) =-4a(6) =7a(7) =-2a(8) =5a(9) =-6a(10) =16a(11) =-14a(12) =10a(13) =0a(14) =7a(15) =-13a(16) =21a(17) =-19a(18) =22a(19) =-10a(20) =4a(21) =-12a(22) =36a(23) =-29a(24) =11a(25) =-2a(26) =16a(27) =-26a(28) =42a(29) =-40