A Chebyshev transform of 3^n.

Terms

a(0) =1a(1) =3a(2) =8a(3) =21a(4) =56a(5) =150a(6) =400a(7) =1065a(8) =2840a(9) =7578a(10) =20208a(11) =53874a(12) =143664a(13) =383148a(14) =1021728a(15) =2724465a(16) =7265240a(17) =19374450a(18) =51665200a(19) =137772246a(20) =367392656a(21) =979719348a(22) =2612584928a(23) =6966873546a(24) =18578329456a(25) =49542281220a(26) =132112749920