a(n) = A000085(4*n+2)/2^(n+1).A316332a(n) = A000085(4*n+2)/2^(n+1).Terms a(0) =1a(1) =19a(2) =1187a(3) =149405a(4) =31166057a(5) =9670072483External referencesoeis: A316332