457763671875domain: NAppears in sequencesExpansion of g.f. (1 - 2*x)/(1 - 5*x).at n=17A005053a(n) = n*5^n.at n=15A036291a(n) = (2*n+1)*5^(2*n+1).at n=7A072172a(n) = (4*5^n + (-5)^n)/5.at n=17A083222