23863649055domain: NAppears in sequencesNumbers k such that k*(k+1)/2 + 1 is a square.at n=27A006451a(n) = 2*a(n-1) + a(n-2) + 1, a(0) = 1, a(1) = 2.at n=27A098790Indices of triangular numbers that are eight times other triangular numbers.at n=13A336625