Dirichlet convolution of sigma(n) with Catalan numbers.

Terms

a(0) =1a(1) =4a(2) =6a(3) =15a(4) =20a(5) =64a(6) =140a(7) =466a(8) =1451a(9) =4928a(10) =16808a(11) =58986a(12) =208026a(13) =743328a(14) =2674532a(15) =9696213a(16) =35357688a(17) =129649324a(18) =477638720a(19) =1767277964a(20) =6564120996a(21) =24466317456a(22) =91482563664a(23) =343059792196