a(n) = 2^n * Sum_{k=0..n} k^p*q^k, where p=2, q=-1/2.

Terms

a(0) =0a(1) =-1a(2) =2a(3) =-5a(4) =6a(5) =-13a(6) =10a(7) =-29a(8) =6a(9) =-69a(10) =-38a(11) =-197a(12) =-250a(13) =-669a(14) =-1142a(15) =-2509a(16) =-4762a(17) =-9813a(18) =-19302a(19) =-38965a(20) =-77530a(21) =-155501a(22) =-310518a(23) =-621565a(24) =-1242554a(25) =-2485733a(26) =-4970790a(27) =-9942309a(28) =-19883834a(29) =-39768509