Approximation of the 2-adic integer arctanh(4) up to 2^n.

Terms

a(0) =0a(1) =0a(2) =0a(3) =4a(4) =4a(5) =4a(6) =4a(7) =68a(8) =196a(9) =196a(10) =708a(11) =1732a(12) =3780a(13) =7876a(14) =7876a(15) =7876a(16) =40644a(17) =106180a(18) =237252a(19) =499396a(20) =1023684a(21) =1023684a(22) =3120836a(23) =7315140a(24) =15703748a(25) =15703748a(26) =49258180a(27) =116367044a(28) =250584772a(29) =250584772