A symmetrical triangle sequence:q=3:t(n,m,q)=(1 - q^n)*Eulerian[n + 1, m] - (1 - q^n) + 1.

Terms

a(0) =1a(1) =1a(2) =1a(3) =1a(4) =-23a(5) =1a(6) =1a(7) =-259a(8) =-259a(9) =1a(10) =1a(11) =-1999a(12) =-5199a(13) =-1999a(14) =1a(15) =1a(16) =-13551a(17) =-72841a(18) =-72841a(19) =-13551a(20) =1a(21) =1a(22) =-86631a(23) =-866319a(24) =-1758119a(25) =-866319a(26) =-86631a(27) =1a(28) =1a(29) =-537755