a(n) = (A112565(n) - 1)/n for n>=1.

Terms

a(0) =1a(1) =3a(2) =9a(3) =31a(4) =109a(5) =421a(6) =1585a(7) =5454a(8) =20681a(9) =80983a(10) =311221a(11) =1168531a(12) =4505761a(13) =17907735a(14) =69240865a(15) =272109736a(16) =1078430833a(17) =4147985381a(18) =16383884581a(19) =64335012378a(20) =234179431201a(21) =929947274509