213500domain: NAppears in sequencesNumber of length n+3 0..7 arrays with every four consecutive terms having the sum of some three elements equal to three times the fourth.at n=15A248536a(n) = n! * [x^n] exp(2*n*x)*BesselI(0,2*x)^n.at n=5A294454a(n) = Sum_{k=1..n} k^2 * n^(n-k).at n=7A368524