20368898563domain: NAppears in sequencesNumbers k such that hexagonal numbers H(k) and H(k+1) sum to another hexagonal number.at n=7A251601a(n) = 2*a(n-1) + 2*a(n-3) + a(n-4) - 1, with a(0) = 0 = a(1), a(2) = 2, and a(3) = 3.at n=29A353582