1879048190domain: NAppears in sequencesa(n) = Sum_{k=0..n} A026615(n, k).at n=30A026622a(0)=1, a(1)=2, a(2)=1; for n>2, a(n) = 7*2^(n-3)-2.at n=31A174317a(n) = 7*2^n - 2.at n=28A176448a(n) - 2*a(n-1) = period 2: repeat [3, 0] for n > 0, a(0)=5, a(1)=13.at n=28A322417