527953domain: NAppears in sequencesa(n) = (1/2) * (5*P(n+1) + P(n) - 1), where P(k) are the Pell numbers A000129.at n=14A098586Nonnegative integers n such that 2n^2 + 2n - 3 is square.at n=15A124124Numbers k where d/k reaches a new record, with d the distance from the k-th triangular number to the nearest square.at n=20A229117