644531250domain: NAppears in sequences5th binomial transform of (0,0,1,0,0,0, ...).at n=12A081135a(n) = 5^(n-1)*n*(n+1)/2.at n=11A084902Denominator of Bernoulli(n, 1/5).at n=10A157867Number of n X 1 0..5 arrays with some element plus some horizontally or vertically adjacent neighbor totalling five exactly once.at n=11A269760