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Numbers n such that n^s(n) + 1 is a prime, where s(n) is the sum of the digits of n.
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%I #7 Aug 26 2019 21:09:21

%S 1,2,4,10,20,100,110,152,220,242,736,790,800,916,1010,1078,1106,1232,

%T 1528,1636,1834,2284,2330,2392,2600,3100,3562,3904,4000,4066,4228,

%U 4444,4552,5056,6082,6208,6226,7810,8170,8530,9520

%N Numbers n such that n^s(n) + 1 is a prime, where s(n) is the sum of the digits of n.

%t t = {}; Do[If[PrimeQ[(n^Total[IntegerDigits[n]]) + 1], AppendTo[t, n]], {n, 10000}]; t

%t Select[Range[10000],PrimeQ[#^Total[IntegerDigits[#]]+1]&] (* _Harvey P. Dale_, Aug 26 2019 *)

%K nonn,base

%O 1,2

%A _Vicente Izquierdo Gomez_, Aug 15 2012