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%I #20 Apr 03 2018 15:13:57
%S 440,600,950,1000,1240,1320,1350,1400,1450,1640,1900,2090,2200,2440,
%T 2600,2700,2840,2850,2900,2950,2970,3000,3080,3190,3400,3720,3800,
%U 3950,3960,4040,4180,4200,4350,4450,4600,4750,4840,4920,5240,5400,5450,5700
%N Last digit of n, phi(n) and sigma(n) is 0 in base 10.
%C This sequence is infinite. 440 * k is in the sequence for odd k > 0 and k, 440 are coprime. - _David A. Corneth_, Apr 01 2018
%H David A. Corneth, <a href="/A072604/b072604.txt">Table of n, a(n) for n = 1..16811</a> (all terms up to 10^6)
%F Does lim n -> infinity a(n)/n exist?
%e phi(1240)=480, sigma(1240)=2880, hence 1240 is in the sequence.
%t Select[Range[6000],Mod[{#,EulerPhi[#],DivisorSigma[1,#]},10]=={0,0,0}&] (* _Harvey P. Dale_, Apr 01 2018 *)
%o (PARI) isok(n) = !(n % 10) && !(eulerphi(n) % 10) && ! (sigma(n) % 10); \\ _Michel Marcus_, Nov 26 2013
%Y Cf. A000010, A000203.
%Y Subsequence of A072589.
%K base,nonn
%O 1,1
%A _Benoit Cloitre_, Aug 06 2002
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