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 A110196 #13 Nov 18 2024 07:30:50
%S A110196 1,13,23,97,113,131,199,227,491,859,929
%N A110196 Numbers m such that k = 2m is the least k such that phi(m+k) = 2*phi(k).
%C A110196 Note that all m > 1 are primes.
%C A110196 No other terms below 10^8. - _Max Alekseyev_, Nov 18 2024
%H A110196 Max Alekseyev, <a href="https://oeis.org/wiki/User:Max_Alekseyev/gpscripts">PARI/GP Scripts for Miscellaneous Math Problems</a> (invphi.gp).
%t A110196 Do[k=1; While[EulerPhi[n+k] != 2*EulerPhi[k], k++ ]; If[k==2n, Print[n]], {n, 5000}]
%o A110196 (PARI) f(n) = apply(x -> x - n, select(x -> x > n, invphi(2*eulerphi(n)))); \\ using _Max Alekseyev_'s invphi.gp
%o A110196 lista(nmax) = {my(v = vector(nmax), c = 0, k = 1, s); while(c < nmax, s = f(k); for(i = 1, #s, if(s[i] <= nmax && v[s[i]] == 0, c++; v[s[i]] = k)); k++); for(i = 1, #v, if(v[i] == 2*i, print1(i, ", ")));} \\ _Amiram Eldar_, Nov 05 2024
%Y A110196 Cf. A000010, A050473 (least k such that phi(n+k) = 2*phi(k)).
%K A110196 nonn,more
%O A110196 1,2
%A A110196 _T. D. Noe_, Jul 15 2005