OFFSET
0,2
LINKS
Vincenzo Librandi, Table of n, a(n) for n = 0..1000
FORMULA
Sum_{k=1..n} a(k) = c * n^4 + O((n*log(n))^3), where c = (83/288) * Product_{primes p == 1 (mod 3)} ((p^2+2)/(p^2-1)) * Product_{primes p == 2 (mod 3)} (p^2/(p^2-1)) = 0.449926279... . - Amiram Eldar, Dec 09 2024
EXAMPLE
a(4) = 84 because 4^3+1 = 65 and the sum of the 4 divisors {1, 5, 13, 65} is 84.
MATHEMATICA
Table[Total[Divisors[n^3 + 1]], {n, 0, 50}]
DivisorSigma[1, Range[0, 40]^3+1] (* Harvey P. Dale, Jul 27 2021 *)
PROG
(Magma) [SumOfDivisors(n^3+1): n in [0..50]];
(PARI) a(n) = sigma(n^3+1); \\ Michel Marcus, Jun 19 2015
CROSSREFS
KEYWORD
nonn,easy
AUTHOR
Vincenzo Librandi, Jan 01 2014
STATUS
approved