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 A091454 #16 Apr 07 2024 09:09:39 %S A091454 30,42,60,66,78,84,90,102,114,120,126,132,138,150,156,168,174,180,186, %T A091454 198,204,210,222,228,234,240,246,252,258,264,270,276,282,294,300,306, %U A091454 312,318,330,336,342,348,354,360,366,372,378,390,396,402,408,414,420 %N A091454 Integers k such that 3*phi(k) < k. %C A091454 If k is present so are all m*k, m>1. %C A091454 The smallest odd number in this sequence is 111546435 = 3*5*7*11*...*23. - _T. D. Noe_, Jan 15 2004 %H A091454 Robert Israel, <a href="/A091454/b091454.txt">Table of n, a(n) for n = 1..10000</a> %p A091454 filter:= n -> 3*numtheory:-phi(n) < n: %p A091454 select(filter, [$1..10000]); # _Robert Israel_, Jan 13 2020 %t A091454 Select[ Range[437], 3EulerPhi[ # ] < # & ] %o A091454 (Magma) [k:k in [1..500]|3*EulerPhi(k) lt k]; // _Marius A. Burtea_, Jan 13 2020 %o A091454 (PARI) is(n) = 3*eulerphi(n) < n; \\ _Amiram Eldar_, Apr 07 2024 %Y A091454 Cf. A000010 (phi), A054741, A066765, A091456. %K A091454 nonn %O A091454 1,1 %A A091454 _Robert G. Wilson v_, Jan 10 2004