

A101294


Numbers n such that omega(n2) = omega(n1) = omega(n) = omega(n+1) = omega(n+2).


2



56, 93, 94, 117, 143, 144, 145, 146, 160, 207, 214, 215, 216, 217, 297, 303, 325, 326, 327, 393, 537, 687, 723, 801, 1137, 1347, 1467, 1537, 1713, 1943, 1983, 2103, 2217, 2304, 2305, 2306, 2427, 2643, 2666, 2716, 3867, 3914, 4413
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OFFSET

1,1


LINKS



EXAMPLE

143 is in the sequence because it has two unique prime factors (11 and 13), the same number as its two nearest neighbors on both sides (141 has 3 and 47, 142 has 2 and 71, 144 has 2 and 3 and 145 has 5 and 29).


MATHEMATICA

For[i=2, i<10000, If[And[Length[FactorInteger[i2]]==Length[FactorInteger[i]], Length[FactorInteger[i1]]==Length[FactorInteger[i]], Length[FactorInteger[i+1]]==Length[FactorInteger[i]], Length[FactorInteger[i+2]]==Length[FactorInteger[i]]], Print[i]]; i++ ]
Select[Range[600000], PrimeNu[#  2] == PrimeNu[#  1] == PrimeNu[#] == PrimeNu[# + 1] == PrimeNu[# + 2] &] (* G. C. Greubel, May 15 2017 *)


CROSSREFS



KEYWORD

easy,nonn


AUTHOR



EXTENSIONS



STATUS

approved



