210664domain: NAppears in sequencesa(n)/4^n is the expected number of tosses of a coin required to obtain n+1 heads or n+1 tails.at n=7A033504Maximum value of the n-th difference of a permutation of 0..n.at n=15A130783a(n) = 289*n^2 - 17.at n=26A158587G.f. A(x) satisfies: A(x) = 1 + x * A(x/(1 - x)^5) / (1 - x)^5.at n=7A351818