a(n) = binomial coefficient C(n,45).

Terms

a(0) =1a(1) =46a(2) =1081a(3) =17296a(4) =211876a(5) =2118760a(6) =18009460a(7) =133784560a(8) =886322710a(9) =5317936260a(10) =29248649430a(11) =148902215280a(12) =707285522580