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A098216 Nonprime numbers n for which cototient[n]=n-phi[n] is a decimal repdigit. 3
1, 4, 6, 8, 9, 10, 12, 14, 15, 16, 21, 25, 27, 30, 35, 49, 60, 86, 90, 93, 120, 121, 145, 159, 172, 175, 195, 231, 245, 253, 279, 291, 327, 365, 497, 535, 559, 693, 703, 737, 886, 979, 981, 993, 1037, 1111, 1121, 1411, 1457, 1517, 1617, 1772, 1774, 2047, 2059 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

LINKS

Table of n, a(n) for n=1..55.

EXAMPLE

n=97002, n-phi[n]=66666

MATHEMATICA

ta={{0}}; Do[s=Length[Union[IntegerDigits[n-EulerPhi[n]]]]; If[Equal[s, 1]&&!PrimeQ[n], Print[{n, n-EulerPhi[n]}]; ta=Append[ta, n]], {n, 1, 100000}]; ta=Delete[ta, 1]; ta-EulerPhi[ta]

CROSSREFS

Cf. A096503, A010785.

Sequence in context: A050655 A117098 A077136 * A341321 A063806 A323521

Adjacent sequences:  A098213 A098214 A098215 * A098217 A098218 A098219

KEYWORD

nonn,base

AUTHOR

Labos Elemer, Oct 22 2004

STATUS

approved

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Last modified May 26 17:16 EDT 2022. Contains 354092 sequences. (Running on oeis4.)