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A291530 a(n) is the smallest k such that uphi(k*n) = uphi(k*n+1), or 0 if no such k exists. 0

%I

%S 1,10,373,5,4,372,5,26,248,2,13,186,11,562,247,13,627,124,195,1,183,

%T 86,245,93,5184,8,185,281,1623,4320,72,738,43,2296,1,62,20,2312,95,

%U 3240,576,732,33,43,111,4600,540100,492,115,2592,209,4,25383,2388,629,549,65,1732,64476,2160,20,36,61

%N a(n) is the smallest k such that uphi(k*n) = uphi(k*n+1), or 0 if no such k exists.

%e a(3) = 373 because uphi(373*3) = uphi(373*3+1) and 373 is the smallest number with this property.

%o (PARI) uphi(n) = my(f=factor(n)); prod(i=1, #f~, f[i, 1]^f[1, 2]-1);

%o a(n) = {my(k = 1); while (uphi(k*n) != uphi(k*n+1), k++); k; }

%Y Cf. A047994, A275412, A287055.

%K nonn

%O 1,2

%A _Altug Alkan_, Aug 25 2017

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Last modified August 9 18:32 EDT 2020. Contains 336326 sequences. (Running on oeis4.)