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Numbers n such that (the sum of the divisors of n) plus (the sum of the squares of the divisors of n) plus (the sum of the cubes of the divisors of n) is a prime number.
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%I #16 Aug 07 2019 12:49:10

%S 1,2,4,18,25,100,484,1089,1156,2809,11449,42025,52900,63001,119716,

%T 120409,196249,218089,220900,280900,310249,407044,491401,594441,

%U 632025,651249,697225,1012036,1062961,1134225,1216609,1240996,1408969,1643524,1646089,1692601

%N Numbers n such that (the sum of the divisors of n) plus (the sum of the squares of the divisors of n) plus (the sum of the cubes of the divisors of n) is a prime number.

%H Amiram Eldar, <a href="/A220586/b220586.txt">Table of n, a(n) for n = 1..500</a>

%t Select[Range[5000000], PrimeQ[DivisorSigma[1,#] + DivisorSigma[2,#] + DivisorSigma[3,#]]&]

%Y Cf. A000040, A000203, A001157, A001158.

%K nonn

%O 1,2

%A _Harvey P. Dale_, Dec 16 2012

%E a(1) = 1 added by _Amiram Eldar_, Aug 07 2019