15754509550domain: NAppears in sequencesa(n) = 2*a(n-1) + 2*a(n-3) + a(n-4), with a(0)=1, a(1)=2, a(3)=4, a(4)=10.at n=27A0899282*A084158 (twice Pell triangles).at n=14A114620Numbers n such that n^2 + n(n+1) is an oblong number (A002378).at n=7A220185