a(n) = sigma(n)*sigma(n+1)/gcd(sigma(n+1), sigma(n))^2.

Terms

a(0) =3a(1) =12a(2) =28a(3) =42a(4) =2a(5) =6a(6) =120a(7) =195a(8) =234a(9) =6a(10) =21a(11) =2a(12) =84a(13) =1a(14) =744a(15) =558a(16) =78a(17) =780a(18) =210a(19) =336a(20) =72a(21) =6a(22) =10a(23) =1860a(24) =1302a(25) =420a(26) =35a(27) =420a(28) =60a(29) =36