Search: id:A000469
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%I A000469
%S A000469 1,6,10,14,15,21,22,26,30,33,34,35,38,39,42,46,51,55,57,58,62,65,66,69,
%T A000469 70,74,77,78,82,85,86,87,91,93,94,95,102,105,106,110,111,114,115,118,
%U A000469 119,122,123,129,130,133,134,138,141,142,143,145,146,154,155,158
%N A000469 1 together with products of >=2 distinct primes.
%C A000469 Nonprime square-free numbers.
%C A000469 Except for 1, composite n such that the square-free part of n is greater 
               than phi(n) - Benoit Cloitre (benoit7848c(AT)orange.fr), Apr 06 2002
%H A000469 T. D. Noe, <a href="b000469.txt">Table of n, a(n) for n=1..10000</a>
%F A000469 n such that A007913(n)>A000010(n) - Benoit Cloitre (benoit7848c(AT)orange.fr), 
               Apr 06 2002
%F A000469 N-floor(N/p1) - floor(N/(p2) - ... -floor(N/p(i) + floor(N/(c2) + floor(N/
               (c3)+ ... + floor(N/c(j)-1 where N is any number; p1,p2 are the primes 
               with p(i) being the first prime > square root of N and c2, c3 are 
               the numbers other than 1 in this sequence with c(j) <= N will yield 
               the number of primes less than or equal to N other than p1,p2,..p(i) 
               - Ben Thurston (benthurston27(AT)yahoo.com), Aug 15 2007
%F A000469 A005171(n))*A008966(a(n)) = 1. [From Reinhard Zumkeller (reinhard.zumkeller(AT)gmail.com), 
               Nov 01 2009]
%t A000469 << NumberTheory`NumberTheoryFunctions` lst={};Do[If[SquareFreeQ[n],If[ 
               !PrimeQ[n],AppendTo[lst,n]]],{n,6!}];lst [From Vladimir Orlovsky 
               (4vladimir(AT)gmail.com), Jan 20 2009]
%o A000469 (PARI) for(n=0,64, if(isprime(n), n+1, if(issquarefree(n),print(n))))
%o A000469 (PARI) for(n=1,160,if(core(n)*(1-isprime(n))>eulerphi(n),print1(n,",")))
%Y A000469 Cf. A005117, A007913, A000010.
%Y A000469 Sequence in context: A119899 A130092 A080365 this_sequence A120944 A052053 
               A006881
%Y A000469 Adjacent sequences: A000466 A000467 A000468 this_sequence A000470 A000471 
               A000472
%K A000469 nonn,easy,nice
%O A000469 1,2
%A A000469 dtb(AT)research.att.com (Dan Bentley)

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