a(n) = Sum_{i=1..n} sigma(i)*sigma(i+1), where sigma(n) = A000203(n) is the sum of the divisors of n.
A330322
a(n) = Sum_{i=1..n} sigma(i)*sigma(i+1), where sigma(n) = A000203(n) is the sum of the divisors of n.
Terms
- a(0) =3a(1) =15a(2) =43a(3) =85a(4) =157a(5) =253a(6) =373a(7) =568a(8) =802a(9) =1018a(10) =1354a(11) =1746a(12) =2082a(13) =2658a(14) =3402a(15) =3960a(16) =4662a(17) =5442a(18) =6282a(19) =7626a(20) =8778a(21) =9642a(22) =11082a(23) =12942a(24) =14244a(25) =15924a(26) =18164a(27) =19844a(28) =22004a(29) =24308
External references
- oeis: A330322