a(n) = 17^n sin(2n arctan(1/4)) or numerator of tan(2n arctan(1/4)).

A067360

a(n) = 17^n sin(2n arctan(1/4)) or numerator of tan(2n arctan(1/4)).

Terms

    a(0) =8a(1) =240a(2) =4888a(3) =77280a(4) =905768a(5) =4839120a(6) =-116593352a(7) =-4896306240a(8) =-113193708472

External references