First differences of A081145.

Terms

a(0) =1a(1) =2a(2) =3a(3) =-4a(4) =5a(5) =6a(6) =-9a(7) =7a(8) =8a(9) =-14a(10) =10a(11) =11a(12) =-18a(13) =12a(14) =13a(15) =-24a(16) =15a(17) =16a(18) =-30a(19) =17a(20) =19a(21) =-34a(22) =20a(23) =21a(24) =-39a(25) =22a(26) =23a(27) =-43a(28) =25a(29) =26