a(n)=n^3-(n-1)^3-(n-2)^3-...-1.

Terms

a(0) =1a(1) =7a(2) =18a(3) =28a(4) =25a(5) =-9a(6) =-98a(7) =-272a(8) =-567a(9) =-1025a(10) =-1694a(11) =-2628a(12) =-3887a(13) =-5537a(14) =-7650a(15) =-10304a(16) =-13583a(17) =-17577a(18) =-22382a(19) =-28100a(20) =-34839a(21) =-42713a(22) =-51842a(23) =-62352a(24) =-74375a(25) =-88049a(26) =-103518a(27) =-120932a(28) =-140447a(29) =-162225