a(n) = Sum_{k=1..n-1} sigma_5(k)*sigma_7(n-k).

Terms

a(0) =0a(1) =1a(2) =162a(3) =6689a(4) =121250a(5) =1296406a(6) =9613604a(7) =54550049a(8) =252178758a(9) =992204376a(10) =3424910566a(11) =10615778966a(12) =30047257318a(13) =78751366604a(14) =193075366412a(15) =446840757793a(16) =982597838280