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 A279289 #21 Jun 27 2025 17:19:24 %S A279289 5,7,9,11,13,14,15,16,17,19,20,21,22,23,25,26,27,28,29,31,32,33,34,35, %T A279289 36,37,38,39,40,41,42,43,44,45,46,47,48,49,50,51,52,53,54,55,56,57,58, %U A279289 59,60,61,62,63,64,65,66,67,68,69,70,71,72,73,74,75,76,77 %N A279289 Numbers k such that phi(k) > tau(k). %C A279289 Numbers k such that A000010(k) > A000005(k). %C A279289 There are 11 numbers k such that phi(k) <= tau(k) and 7 numbers k such that phi(k) = tau(k); see A020490 and A020488. %C A279289 For k >= 31; phi(k) - tau(k) >= 1, see A063070. %F A279289 a(n) = n + 11 for n >= 20. %e A279289 14 is a term because phi(14) = 6 > tau(14) = 4. %t A279289 Select[Range@ 77, EulerPhi@ # > DivisorSigma[0, #] &] (* _Michael De Vlieger_, Dec 11 2016 *) %o A279289 (Magma) [n: n in[1..1000] | EulerPhi(n) gt NumberOfDivisors(n)]; %o A279289 (PARI) is(n) = eulerphi(n) > numdiv(n) \\ _Felix Fröhlich_, Dec 09 2016 %o A279289 (PARI) a(n)=if(n<20, select(k -> eulerphi(k)>numdiv(k), [5..29])[n], n+11) \\ _Charles R Greathouse IV_, Dec 16 2016 %Y A279289 Complement of A020490. %Y A279289 Cf. A000005, A000010, A020488, A020491, A063070, A279287, A279288. %K A279289 nonn %O A279289 1,1 %A A279289 _Jaroslav Krizek_, Dec 09 2016