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A354038
Numbers k such that sum of the proper divisors of k is a multiple of 4.
2
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.
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
KEYWORD
nonn
AUTHOR
Antti Karttunen, May 16 2022
STATUS
approved