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 A067799 #15 May 21 2022 08:42:13 %S A067799 2,3,5,115,143,287,371,413,623,791,4067,10031,24149,32335,39689,88403, %T A067799 93443,107365,148735,168833,212993,427763,555947,650095,925253, %U A067799 1017821,1117457,1139467,1229327,1270801,1407295,2184221,2294509,2913757,3258355,4699981,5747291 %N A067799 Numbers k such that phi(k) + phi(k+1) = sigma(k). %H A067799 Amiram Eldar, <a href="/A067799/b067799.txt">Table of n, a(n) for n = 1..138</a> %t A067799 Select[Range[10^6], EulerPhi[#] + EulerPhi[# + 1] == DivisorSigma[1, #] &] (* _Amiram Eldar_, May 21 2022 *) %Y A067799 Cf. A000010, A000203, A092404. %K A067799 nonn %O A067799 1,1 %A A067799 _Benoit Cloitre_, Feb 07 2002 %E A067799 More terms from _Dean Hickerson_, Feb 16 2002 %E A067799 More terms from _Amiram Eldar_, May 21 2022