a(n) = Sum_{k=0..n} k^p*q^k for p = 2 and q = -2.

Terms

a(0) =0a(1) =-2a(2) =14a(3) =-58a(4) =198a(5) =-602a(6) =1702a(7) =-4570a(8) =11814a(9) =-29658a(10) =72742a(11) =-175066a(12) =414758a(13) =-969690a(14) =2241574a(15) =-5131226a(16) =11645990a(17) =-26233818a(18) =58700838a(19) =-130567130a(20) =288863270a(21) =-635980762a(22) =1394062374a(23) =-3043511258a(24) =6620165158