2549421domain: NAppears in sequencesa(n) = Fibonacci(n) * (Fibonacci(n+2) - 1).at n=15A143212Number of n-variations of the set {1,2,...,n+1} satisfying p(i)-i in {-2,0,2}, i=1..n (an n-variation of the set N_{n+s} = {1,2,...,n+s} is any 1-to-1 mapping p from the set N_n = {1,2,...,n} into N_{n+s} = {1,2,...,n+s}).at n=30A217694