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%I #27 Oct 16 2023 01:38:42
%S 5,10,15,30,60,90,140,420,1170,2480,3360,6200,7440,8190,18600,40640,
%T 114660,121920,131040,297600,997920,2618880,5059200,64995840,72602880,
%U 95472000,102136320,167751680,197308800,433305600,503255040,668304000,714954240,1307124000,1381161600,1502582400
%N Numbers k such that gcd(sigma(k),k) = k/5.
%C Also numbers k such that denominator(sigma(k)/k) = 5. - _David A. Corneth_, Oct 15 2023
%H David A. Corneth, <a href="/A067237/b067237.txt">Table of n, a(n) for n = 1..166</a> (first 61 terms from Jud McCranie, terms <= 10^28)
%e 30 is in the sequence as gcd(sigma(30), 30) = gcd(72, 30) = 6 = 30/5. - _David A. Corneth_, Oct 15 2023
%o (PARI) is(n) = gcd(sigma(n), n) == n/5 - _David A. Corneth_, Oct 15 2023
%Y Cf. A000203.
%Y Cf. similar sequences with A017666(n)=k: A159907 (k=2), A245775 (k=3), A229088 (k=4), A262359 (k=6).
%K nonn
%O 1,1
%A _Benoit Cloitre_, Feb 20 2002
%E More terms from Sam Handler (sam_5_5_5_0(AT)yahoo.com), Nov 15 2004