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A067290 Numbers n such that prime(n)<n*tau(n) where tau(n) is the number of divisors of n. 1

%I #16 Oct 16 2016 09:49:14

%S 2,3,4,6,8,9,10,12,14,15,16,18,20,21,22,24,26,27,28,30,32,36,40,42,44,

%T 45,48,50,52,54,56,60,63,64,66,68,70,72,75,76,78,80,84,88,90,92,96,98,

%U 99,100,102,104,105,108,110,112,114,116,117,120,124,126,128,130,132

%N Numbers n such that prime(n)<n*tau(n) where tau(n) is the number of divisors of n.

%C Visible sharp bends on the graph around the 500th and 15000th terms occur where the ratio prime(n)/n exceeds 8 and 12, correspondingly. - _Ivan Neretin_, Oct 16 2016

%H Ivan Neretin, <a href="/A067290/b067290.txt">Table of n, a(n) for n = 1..20000</a>

%t Select[Range@135, Prime[#] < #*DivisorSigma[0, #] &] (* _Ivan Neretin_, Oct 16 2016 *)

%o (PARI) for(n=1,171, if(prime(n)<n*numdiv(n),print1(n,",")))

%Y Cf. A000005.

%K nonn

%O 1,1

%A _Benoit Cloitre_, Feb 24 2002

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Last modified April 24 20:08 EDT 2024. Contains 371963 sequences. (Running on oeis4.)