58720254domain: NAppears in sequencesa(n) = Sum_{k=0..n} A026615(n, k).at n=25A026622a(n) = T(3,n), array T given by A047858.at n=22A047860a(0)=1, a(1)=2, a(2)=1; for n>2, a(n) = 7*2^(n-3)-2.at n=26A174317a(n) = 7*2^n - 2.at n=23A176448