a(n) = 3^n*A168053(n).

Terms

a(0) =1a(1) =3a(2) =-9a(3) =-81a(4) =-243a(5) =-1215a(6) =-5103a(7) =-15309a(8) =-59049a(9) =-216513a(10) =-649539a(11) =-2302911a(12) =-7971615a(13) =-23914845a(14) =-81310473a(15) =-272629233a(16) =-817887699a(17) =-2711943423a(18) =-8910671247a(19) =-26732013741a(20) =-87169610025a(21) =-282429536481a(22) =-847288609443