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A318937
a(n) = 16 times the sum of the cubes of the divisors of 2*n+1.
1
16, 448, 2016, 5504, 12112, 21312, 35168, 56448, 78624, 109760, 154112, 194688, 252016, 327040, 390240, 476672, 596736, 693504, 810464, 984704, 1102752, 1272128, 1526112, 1661184, 1887888, 2201472, 2382048, 2685312, 3073280, 3286080, 3631712, 4166528, 4431168, 4812224
OFFSET
0,1
LINKS
P. J. C. Lamont, The number of Cayley integers of given norm, Proceedings of the Edinburgh Mathematical Society, 25.1 (1982): 101-103. See (6).
FORMULA
Sum_{k=0..n} a(k) ~ 30*zeta(4) * n^4. - Amiram Eldar, Dec 12 2023
MAPLE
with(numtheory);
rJ0 := proc(k) local n, d; n:=2*k+1; 16*add(d^3, d in divisors(n)); end;
[seq(rJ0(k), k=0..60)];
MATHEMATICA
16 DivisorSigma[3, Range[1, 75, 2]] (* Vincenzo Librandi, Sep 16 2018 *)
PROG
(Magma) [16*DivisorSigma(3, 2*n+1): n in [0..40]]; // Vincenzo Librandi, Sep 16 2018
CROSSREFS
Equals 16 times A045823.
Cf. A013662.
Sequence in context: A068792 A229583 A241077 * A358569 A368772 A253446
KEYWORD
nonn,easy
AUTHOR
N. J. A. Sloane, Sep 15 2018
STATUS
approved