116721domain: NAppears in sequencesa(n) = n^4 - 6*n^3 + 12*n^2 - 4*n + 1.at n=20A027382G.f.: Product_{k>=1} (1 + x^(k*(k+1)/2)) / (1 - x^k).at n=38A280421a(n) = p(2,n), where p(x,n) is the strong divisibility sequence of polynomials based on sqrt(5) as in A327322.at n=4A329013