The Zeta triangle.

Terms

a(0) =-1a(1) =51a(2) =-10a(3) =-10594a(4) =2961a(5) =-210a(6) =356487a(7) =-115940a(8) =12642a(9) =-420a(10) =-101141295a(11) =35804857a(12) =-4751890a(13) =254562a(14) =-4620a(15) =48350824787a(16) =-18071509911a(17) =2689347661a(18) =-180909586a(19) =5471466a(20) =-60060