a(n) = abs(A154879(n+1)).

Terms

a(0) =2a(1) =4a(2) =0a(3) =8a(4) =8a(5) =24a(6) =40a(7) =88a(8) =168a(9) =344a(10) =680a(11) =1368a(12) =2728a(13) =5464a(14) =10920a(15) =21848a(16) =43688a(17) =87384a(18) =174760a(19) =349528a(20) =699048a(21) =1398104a(22) =2796200a(23) =5592408a(24) =11184808a(25) =22369624a(26) =44739240a(27) =89478488a(28) =178956968a(29) =357913944