

A006073


Numbers n such that n, n+1 and n+2 all have same number of distinct prime divisors.


14



2, 3, 7, 20, 33, 34, 38, 44, 50, 54, 55, 56, 74, 75, 85, 86, 91, 92, 93, 94, 98, 115, 116, 117, 122, 133, 134, 141, 142, 143, 144, 145, 146, 158, 159, 160, 175, 176, 183, 187, 200, 201, 205, 206, 207, 212, 213, 214, 215, 216, 217, 224, 235, 247
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OFFSET

1,1


COMMENTS

Distinct prime divisors means that the prime divisors are counted without multiplicity.  Harvey P. Dale, Apr 19 2011


LINKS

Harvey P. Dale, Table of n, a(n) for n = 1..10000


MATHEMATICA

pdQ[n_]:=PrimeNu[n]==PrimeNu[n+1]==PrimeNu[n+2]; Select[Range[250], pdQ] (* Harvey P. Dale, Apr 19 2011 *)
Take[Transpose[Flatten[Select[Partition[{#, PrimeNu[#]}&/@Range[250000], 3, 1], #[[1, 2]]==#[[2, 2]]==#[[3, 2]]&], 1]][[1]], {1, 1, 3}] (* Harvey P. Dale, Dec 09 2011 *)
Flatten[Position[Partition[PrimeNu[Range[250]], 3, 1], _?(#[[1]]==#[[2]]== #[[3]]&), {1}, Heads>False]] (* Harvey P. Dale, Oct 30 2013 *)


CROSSREFS

Cf. A006049, A045932.
Sequence in context: A172976 A171655 A293683 * A052402 A300041 A222939
Adjacent sequences: A006070 A006071 A006072 * A006074 A006075 A006076


KEYWORD

nonn


AUTHOR

N. J. A. Sloane


STATUS

approved



