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A101940 Numbers n with omega(n) < omega of 3 nearest larger and 3 nearest smaller neighbors. 1
37, 53, 89, 97, 113, 121, 157, 163, 173, 211, 223, 233, 251, 263, 277, 289, 293, 307, 317, 331, 337, 343, 353, 367, 373, 379, 383, 389, 397, 401, 409, 439, 443, 449, 457, 467, 479, 487, 491, 499, 503, 529, 541, 547, 557, 563, 577, 587 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

LINKS

G. C. Greubel, Table of n, a(n) for n = 1..10000

EXAMPLE

37 is in the sequence because it has one unique prime factor (itself), whereas 34, 35, 36, 38, 39 and 40 each have more.

MATHEMATICA

For[i=1, i<1000, If[And[Length[FactorInteger[i-3]] > Length[FactorInteger[i]], Length[FactorInteger[i-2]]>Length[FactorInteger[i]], Length[FactorInteger[i-1]]>Length[FactorInteger[i]], Length[FactorInteger[i+1]]> Length[FactorInteger[i]], Length[FactorInteger[i+2]]> Length[FactorInteger[i]], Length[FactorInteger[i+3]]> Length[FactorInteger[i]]], Print[i]]; i++ ]

Select[Range[6500], PrimeNu[#] < Min[PrimeNu[# - 1], PrimeNu[# - 2], PrimeNu[# - 3], PrimeNu[# + 1], PrimeNu[# + 2], PrimeNu[# + 3]] &] (* G. C. Greubel, May 21 2017 *)

CROSSREFS

Cf. A001221, A101934, A101938.

Sequence in context: A101938 A060330 A214755 * A036540 A225214 A141166

Adjacent sequences:  A101937 A101938 A101939 * A101941 A101942 A101943

KEYWORD

easy,nonn

AUTHOR

Neil Fernandez, Dec 21 2004

STATUS

approved

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Last modified September 26 05:09 EDT 2017. Contains 292502 sequences.