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 A067883 #31 Aug 10 2024 22:34:27 %S A067883 1,2,4,6,8,12,48,60,72,96,128,240,432,480,720,1728,2016,6912,10368, %T A067883 14080,32768,142560,184320,196560,712800,1140480,1190400,1658880, %U A067883 1801800,3345408,3571200,5702400,6220800,8363520,10222080,10368000,14859936,29719872,50319360 %N A067883 Numbers k such that k = phi(sigma(phi(sigma(k)))). %C A067883 This sequence has both terms of cycles of length 2 when iterating k <-phi(sigma(k)) (see A373435) plus cycles of length 1 (see A001229). - _Jud McCranie_, Aug 09 2024 %t A067883 Select[Range[10^6], EulerPhi[DivisorSigma[1, EulerPhi[DivisorSigma[1, #]]]] == # &] (* _Amiram Eldar_, Apr 24 2022 *) %Y A067883 Cf. A000010, A000203, A062401, A163372. %Y A067883 Supersequence of A001229. A373435 is a subsequence of this sequence. %K A067883 easy,nonn %O A067883 1,2 %A A067883 _Benoit Cloitre_, Mar 02 2002 %E A067883 More terms from _Reiner Martin_, Jul 09 2002 %E A067883 a(35)-a(39) from _Amiram Eldar_, Apr 24 2022