147737domain: NAppears in sequencesa(1)=7; a(n),a(n+1) are smallest > a(n-1) such that a(n-1)^2+a(n)^2=a(n+1)^2.at n=14A077035Pentagonal numbers (A000326) that are also brilliant numbers (A078972).at n=18A113941Semiprimes of the form n*(3*n-1)/2.at n=32A245365Semiprimes of the form p(6p - 1).at n=19A330409