A195088 Numbers k such that (number of prime factors of k counted with multiplicity) less (number of distinct prime factors of k) = 4.

32, 96, 144, 160, 216, 224, 243, 324, 352, 400, 416, 480, 486, 544, 608, 672, 720, 736, 784, 928, 992, 1000, 1008, 1056, 1080, 1120, 1184, 1200, 1215, 1248, 1312, 1376, 1504, 1512, 1584, 1620, 1632, 1696, 1701, 1760, 1800, 1824, 1872, 1888, 1936, 1952

Offset

1,1

Comments

The asymptotic density of this sequence is (6/Pi^2) * Sum_{k>=1} f(a(k)) = 0.0237194..., where f(k) = A112526(k) * Product_{p|k} p/(p+1). - Amiram Eldar, Sep 24 2024

Links

Reinhard Zumkeller, Table of n, a(n) for n = 1..10000

Index entries for sequences computed from exponents in factorization of n.

Formula

A046660(a(n)) = 4. - Reinhard Zumkeller, Nov 29 2015

Mathematica

Select[Range[2000], PrimeOmega[#]-PrimeNu[#]==4&]

Prog

(PARI) is(n)=bigomega(n)-omega(n)==4 \\ Charles R Greathouse IV, Sep 14 2015
(Haskell)
a195088 n = a195088_list !! (n-1)
a195088_list = filter ((== 4) . a046660) [1..]
-- Reinhard Zumkeller, Nov 29 2015

Crossrefs

Cf. A060687, A195069, A195086, A195087, A195089, A195090, A195091, A195092, A195093.

Cf. A025487, A046660, A059956, A112526, A257851, A261256, A264959.

Sequence in context: A126386 A208635 A259715 * A050429 A362841 A044219

Adjacent sequences: A195085 A195086 A195087 * A195089 A195090 A195091

Keyword

nonn,easy

Author

Harvey P. Dale, Sep 08 2011

Status

approved