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A111371 A number n is included if at least one prime dividing n is equal to an exponent of the highest power of any prime dividing n. 0
4, 12, 18, 20, 24, 27, 28, 36, 44, 50, 52, 54, 60, 68, 72, 76, 84, 90, 92, 98, 100, 108, 116, 120, 124, 126, 132, 135, 140, 144, 148, 150, 156, 160, 164, 168, 172, 180, 188, 189, 196, 198, 200, 204, 212, 216, 220, 228, 234, 236, 242, 244, 252, 260, 264, 268, 270 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

LINKS

Table of n, a(n) for n=1..57.

EXAMPLE

50 = 2^1 * 5^2. 2 is both a prime dividing 50 and the exponent of the highest power of 5 dividing 50. So 50 is in the sequence.

MATHEMATICA

Select[Range[2, 300], Intersection @@ Transpose[FactorInteger[ # ]] != {} &] (*Chandler*)

fQ[n_] := Block[{fi = FactorInteger[n]}, Position[ First[ # ] & /@ fi, Max[ Last[ # ] & /@ fi]] != {}]; Select[ Range[2, 291], fQ[ # ] &] (* Robert G. Wilson v *)

CROSSREFS

Sequence in context: A300747 A303795 A175704 * A078514 A230628 A074285

Adjacent sequences:  A111368 A111369 A111370 * A111372 A111373 A111374

KEYWORD

nonn

AUTHOR

Leroy Quet, Nov 08 2005

EXTENSIONS

Extended by Ray Chandler and Robert G. Wilson v, Nov 09 2005

STATUS

approved

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Last modified October 20 22:23 EDT 2018. Contains 316404 sequences. (Running on oeis4.)