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A175875 Numbers n such that sigma(n+3) = 3*sigma(n). 3

%I

%S 3,30237,292317,3116957,4044037,6902277,73442597,115767957,137410557,

%T 416776357,526908197,541579497,695350653,758403357,1105731897,

%U 1178082357,1233277917,1309742557,1866261597,1998267037,2161411557,2563416237,2750761437,2873771997,2892203997,3331848517,3621735037,3758847117

%N Numbers n such that sigma(n+3) = 3*sigma(n).

%C a(1) = A175874(3).

%H Giovanni Resta, <a href="/A175875/b175875.txt">Table of n, a(n) for n = 1..180</a> (terms < 10^12)

%o (PARI) isok(n) = sigma(n+3) == 3*sigma(n); \\ _Michel Marcus_, Oct 19 2013

%o (MAGMA) [n: n in [1..10^8] | SumOfDivisors(n+3) eq 3*SumOfDivisors(n)]; // _Vincenzo Librandi_, Jul 28 2017

%Y Cf. A000203, A002961, A175874, A272027 (3*sigma(n)).

%K nonn

%O 1,1

%A _Zak Seidov_, Oct 06 2010

%E a(8)-a(21) from _Donovan Johnson_, Oct 11 2010

%E a(22)-a(24) from _Donovan Johnson_, Sep 10 2012

%E a(25) from _Zak Seidov_, Jul 07 2013

%E a(26)-a(28) from _Chai Wah Wu_, Jul 27 2017

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Last modified May 8 19:28 EDT 2021. Contains 343666 sequences. (Running on oeis4.)