a(n) = (2^(n^2) - 1)/(1 - 1/2^n).A275779a(n) = (2^(n^2) - 1)/(1 - 1/2^n).Terms a(0) =2a(1) =20a(2) =584a(3) =69904a(4) =34636832a(5) =69810262080External referencesoeis: A275779