This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.
%I A067237 #27 Oct 16 2023 01:38:42 %S A067237 5,10,15,30,60,90,140,420,1170,2480,3360,6200,7440,8190,18600,40640, %T A067237 114660,121920,131040,297600,997920,2618880,5059200,64995840,72602880, %U A067237 95472000,102136320,167751680,197308800,433305600,503255040,668304000,714954240,1307124000,1381161600,1502582400 %N A067237 Numbers k such that gcd(sigma(k),k) = k/5. %C A067237 Also numbers k such that denominator(sigma(k)/k) = 5. - _David A. Corneth_, Oct 15 2023 %H A067237 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 A067237 30 is in the sequence as gcd(sigma(30), 30) = gcd(72, 30) = 6 = 30/5. - _David A. Corneth_, Oct 15 2023 %o A067237 (PARI) is(n) = gcd(sigma(n), n) == n/5 - _David A. Corneth_, Oct 15 2023 %Y A067237 Cf. A000203. %Y A067237 Cf. similar sequences with A017666(n)=k: A159907 (k=2), A245775 (k=3), A229088 (k=4), A262359 (k=6). %K A067237 nonn %O A067237 1,1 %A A067237 _Benoit Cloitre_, Feb 20 2002 %E A067237 More terms from Sam Handler (sam_5_5_5_0(AT)yahoo.com), Nov 15 2004