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 A332972 #10 Mar 05 2020 03:40:42 %S A332972 3,4,105,165,195,2205,2835,38805,131145,407925,936495,1025505,1231425, %T A332972 1276905,1788255,1925565,2521695,2792145,2847585,3289935,5003745, %U A332972 5295885,5710089,6315309,6986889,13496385,17168085,19210065,20171385,22348365,26879685,27798705 %N A332972 Solutions k of the equation cototient(k) = cototient(k-1) + cototient(k-2) where cototient(k) is A051953. %H A332972 Amiram Eldar, <a href="/A332972/b332972.txt">Table of n, a(n) for n = 1..176</a> %e A332972 3 is a term since cototient(3) = 1 and cototient(1) + cototient(2) = 0 + 1 = 1. %e A332972 105 is a term since cototient(105) = 57 and cototient(103) + cototient(104) = 1 + 56 = 57. %t A332972 cotot[n_] := n - EulerPhi[n]; Select[Range[3, 10^6], cotot[#] == cotot[# - 1] + cotot[# - 2] &] %Y A332972 Cf. A051953, A065557, A065900, A075565, A076136, A076251, A145469, A291126, A291176, A292033, A294995. %K A332972 nonn %O A332972 1,1 %A A332972 _Amiram Eldar_, Mar 04 2020