64981domain: NAppears in sequencesNumber of intersections of diagonals in the interior of a regular n-gon.at n=37A006561Sum of squares of numbers that can be written as t*n + u*(n+1) for nonnegative integers t,u in exactly one way.at n=5A076460Semiprimes of the form 5*n^2 + 1.at n=33A212707