a(n) = (1/(6*n)) * Sum_{d|n} mu(n/d) * binomial(6*d,d).

A346580

a(n) = (1/(6*n)) * Sum_{d|n} mu(n/d) * binomial(6*d,d).

Terms

    a(0) =1a(1) =5a(2) =45a(3) =440a(4) =4750a(5) =54081a(6) =642341a(7) =7861216a(8) =98480286a(9) =1256564750a(10) =16273981757a(11) =213378921432

External references