7344000

Appears in sequences

• Molecular topological indices of the square graphs.at n=15A192839
• a(n) is the number of permutations {c_1..c_n} of {1..n} for which c_1 - c_2 + ... + (-1)^(n-1)*c_n are squares.at n=11A293857
• a(n) = phi(10^n-1)/n, where phi is Euler's totient function (A000010).at n=7A295497