Dirichlet convolution of sigma(n) with Bell numbers.

Terms

a(0) =1a(1) =4a(2) =6a(3) =15a(4) =21a(5) =74a(6) =211a(7) =914a(8) =4161a(9) =21216a(10) =115987a(11) =678800a(12) =4213611a(13) =27645078a(14) =190899418a(15) =1382961257a(16) =10480142165a(17) =82864882508a(18) =682076806179