49178domain: NAppears in sequencesNumber of lower triangles of a 5 X 5 0..n array with each element differing from all of its horizontal and vertical neighbors by one.at n=18A195001a(n) = 48*2^n + 26 (n>=1).at n=9A304605a(n) = Sum_{k=1..n} gcd(k,n)^(n/gcd(k,n) - 1).at n=25A342437a(n) = 3*2^n + 2*n - 2.at n=14A381790