A364100 Sum of divisors of 5*n-1 of form 5*k+4.

4, 9, 14, 19, 28, 29, 34, 39, 48, 49, 63, 59, 68, 69, 74, 79, 102, 89, 94, 108, 108, 109, 133, 119, 128, 129, 134, 139, 181, 149, 168, 159, 168, 169, 203, 179, 188, 198, 194, 199, 242, 228, 214, 219, 242, 229, 282, 239, 248, 249, 254, 259, 336, 269, 274, 288, 288, 289, 357, 299, 327, 309, 314, 348

Offset

1,1

Links

Table of n, a(n) for n=1..64.

Formula

a(n) = A284103(5*n-1).

G.f.: Sum_{k>0} (5*k-1) * x^k / (1 - x^(5*k-1)).

Mathematica

a[n_] := DivisorSum[5*n - 1, # &, Mod[#, 5] == 4 &]; Array[a, 100] (* Amiram Eldar, Jul 17 2023 *)

Prog

(PARI) a(n) = sumdiv(5*n-1, d, (d%5==4)*d);

Crossrefs

Cf. A364101, A364102, A364103.

Cf. A284103, A359233, A364104.

Sequence in context: A313128 A313129 A313130 * A313131 A045293 A313132

Adjacent sequences: A364097 A364098 A364099 * A364101 A364102 A364103

Keyword

nonn

Author

Seiichi Manyama, Jul 04 2023

Status

approved