153745domain: NAppears in sequencesNumbers k such that the continued fraction for sqrt(k) has odd period and if the last term of the periodic part is deleted the two central terms are both 87.at n=1A031675Indices of primes in sequence defined by A(0) = 17, A(n) = 10*A(n-1) + 27 for n > 0.at n=21A102034