201408domain: NAppears in sequencesa(1) = 1, a(m+1) = 2*Sum_{k=1..floor((m+1)/2)} a(m+1-k).at n=12A039721Number of essentially different permutations of the numbers 1 to n such that the sum of adjacent numbers is a square.at n=26A090460a(n) = (n^5 - 5*n^4 + 5*n^3 + 5*n^2 + 114*n + 120)/120.at n=31A161701