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 A131826 #11 Apr 08 2023 05:01:42
%S A131826 1,4,9,25,10,26,34,38,30,52,74,76,82,122,90,134,146,148,114,130,194,
%T A131826 202,206,170,226,244,186,268,292,228,290,386,388,398,404,412,370,482,
%U A131826 366,488,434,514,430,584,518,578,614,626,450,674,462,580,610,746,558,772
%N A131826 a(n) is the unique solution to Cototient(x) = A131825(n).
%H A131826 Amiram Eldar, <a href="/A131826/b131826.txt">Table of n, a(n) for n = 1..15628</a>
%e A131826 a(5) = 10 is the unique solution to Cototient(x) = A131825(5) = 6.
%o A131826 (PARI) lista(nn) = {my(c, r, v=vector(nn^2+2, i, i - eulerphi(i))); for(k=0, nn, c=0; for(i=1, k*k+2, if(k==v[i], r=i; c++)); if(c==1, print1(r, ", "))); } \\ _Jinyuan Wang_, Mar 22 2020
%Y A131826 Cf. A051953, A063742, A131825.
%K A131826 nonn
%O A131826 1,2
%A A131826 _Franz Vrabec_, Jul 20 2007
%E A131826 More terms from _Jinyuan Wang_, Mar 22 2020