A054012 Nonzero values of n read modulo (number of proper divisors of n).
2, 1, 1, 2, 2, 3, 1, 3, 1, 2, 3, 2, 2, 1, 2, 4, 2, 5, 4, 1, 3, 1, 2, 5, 1, 1, 5, 2, 3, 4, 2, 3, 3, 6, 2, 1, 2, 1, 8, 1, 1, 7, 1, 2, 4, 2, 1, 2, 1, 2, 8, 3, 4, 4, 4, 6, 1, 9, 5, 4, 2, 1, 1, 2, 1, 2, 1, 2, 4, 2, 5, 2, 4, 1, 2, 2, 3, 5, 8, 1, 2, 4, 1, 2, 2, 3, 7, 5, 3, 2, 2, 2, 6, 2, 4, 4, 1, 3, 1, 2, 1, 2, 6, 5, 1
Offset: 1
Keywords
Programs
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Maple
with(numtheory): [seq(`if`(i mod (tau(i)-1) <> 0,i mod (tau(i)-1),print( )), i=2..220)];
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Mathematica
Cases[Table[Mod[n,DivisorSigma[0,n]-1],{n,2,200}],Except[0]] (* Harvey P. Dale, Nov 12 2011 *)