a(0) = 4; a(n) = a(n-1)^2 - 1.A139244a(0) = 4; a(n) = a(n-1)^2 - 1.Terms a(0) =4a(1) =15a(2) =224a(3) =50175a(4) =2517530624External referencesoeis: A139244