A354038 Numbers k such that sum of the proper divisors of k is a multiple of 4.

1, 9, 10, 12, 24, 26, 28, 34, 44, 48, 49, 56, 58, 60, 74, 76, 81, 82, 84, 88, 90, 92, 96, 106, 108, 112, 120, 121, 122, 124, 132, 140, 146, 152, 156, 168, 172, 176, 178, 184, 188, 192, 194, 202, 204, 216, 218, 220, 224, 226, 228, 234, 236, 240, 248, 252, 260, 264, 268, 274, 276, 280, 284, 298, 300, 304, 306, 308

Offset

1,2

Comments

Numbers k for which A001065(k) = 4*m for some m.

Links

Table of n, a(n) for n=1..68.

Index entries for sequences related to sigma(n)

Formula

{k | A010873(k) == A105824(k)}.

Mathematica

Select[Range[300], Divisible[DivisorSigma[1, #] - #, 4] &] (* Amiram Eldar, May 16 2022 *)

Prog

(PARI)
A354037(n) = (0==((sigma(n)-n)%4));
isA354038(n) = A354037(n);

Crossrefs

Cf. A000203, A001065, A010873, A105824, A354037 (characteristic function).

Sequence in context: A078459 A156345 A078390 * A216780 A279731 A037408

Adjacent sequences: A354035 A354036 A354037 * A354039 A354040 A354041

Keyword

nonn

Author

Antti Karttunen, May 16 2022

Status

approved