A363291 Sum of divisors of 4*n-1 of form 4*k+1.

1, 1, 1, 6, 1, 1, 10, 1, 6, 14, 1, 1, 18, 6, 1, 31, 1, 1, 31, 1, 1, 30, 14, 6, 43, 1, 1, 38, 6, 18, 42, 1, 1, 60, 1, 14, 71, 1, 6, 54, 1, 1, 67, 31, 1, 62, 18, 1, 84, 1, 30, 79, 1, 6, 74, 1, 1, 132, 6, 1, 91, 14, 1, 108, 38, 1, 90, 1, 31, 103, 1, 42, 98, 6, 14, 102, 1, 1, 186, 30, 18, 110, 1, 6, 114, 50, 1

Offset

1,4

Links

Table of n, a(n) for n=1..87.

Formula

a(n) = A050449(4*n-1).

G.f.: Sum_{k>0} (4*k-3) * x^(3*k-2) / (1 - x^(4*k-3)).

Mathematica

a[n_] := DivisorSum[4*n - 1, # &, Mod[#, 4] == 1 &]; Array[a, 100] (* Amiram Eldar, Jul 08 2023 *)

Prog

(PARI) a(n) = sumdiv(4*n-1, d, (d%4==1)*d);

Crossrefs

Cf. A050449, A078703, A364082.

Sequence in context: A174377 A176151 A204001 * A144395 A046621 A046617

Adjacent sequences: A363288 A363289 A363290 * A363292 A363293 A363294

Keyword

nonn

Author

Seiichi Manyama, Jul 08 2023

Status

approved