1470878640domain: NAppears in sequencesNumbers k such that k*(k+1)/2 + 1 is a square.at n=24A006451a(n) = (1/2) * (5*P(n+1) + P(n) - 1), where P(k) are the Pell numbers A000129.at n=23A098586Indices of triangular numbers that are eight times other triangular numbers.at n=12A336625