A057852 - OEIS

A057852

Numbers n such that n | Sigma_2(n) + Sigma_1(n) + Sigma_0(n).

1, 2, 6, 8, 27, 30, 42, 60, 130, 611, 837, 1196, 7524, 10640, 14160, 16836, 43268, 59856, 83121, 90960, 317424, 688704, 718643, 769101, 4714800, 11339016, 15819208, 25553726, 37282080, 53056400, 97012042, 190740298, 403501008, 2047926288

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OFFSET

1,2

COMMENTS

sigma_0(n) is the number of divisors of n (A000005).

sigma_1(n) is the sum of the divisors of n [same as sigma(n)] (A000203).

sigma_2(n) is the sum of the squares of the divisors of n (A001157).

LINKS

Table of n, a(n) for n=1..34.

MATHEMATICA

Do[ If[ Mod[ DivisorSigma[ 2, n] + DivisorSigma[ 1, n] + DivisorSigma[ 0, n], n] == 0, Print[n]], {n, 1, 10^7}]

With[{c=Total[Table[DivisorSigma[x, #], {x, 0, 2}]]}, Select[Range[800000], Mod[c, #]==0&]] (* Harvey P. Dale, May 23 2023 *)

CROSSREFS

Sequence in context: A116083 A115506 A243552 * A180814 A290679 A290423

Adjacent sequences: A057849 A057850 A057851 * A057853 A057854 A057855

KEYWORD

nonn

AUTHOR

Robert G. Wilson v, Nov 10 2000

EXTENSIONS

a(26)-a(34) from Donovan Johnson, Jun 08 2011

STATUS

approved