81475594253domain: NAppears in sequencesa(n) = 6*a(n-1) - a(n-2), n >= 2, a(0)=1, a(1)=9.at n=14A0387612*a(n)^2 + 7 is a square.at n=28A077442a(2n) = A001542(n+1), a(2n+1) = A038761(n+1); a Pellian-related sequence.at n=27A129345