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 A074634 #8 Jan 22 2025 22:26:19
%S A074634 1,1,2,1,2,4,1,2,4,9,1,2,4,9,6,1,2,4,9,6,25,1,2,4,9,6,18,10,1,2,4,9,6,
%T A074634 25,10,15,1,2,4,9,6,25,10,15,12,1,2,4,9,6,25,10,15,12,21,1,2,4,9,6,24,
%U A074634 10,15,12,21,45,1,2,4,9,6,25,10,15,12,21,30,35,1,2,4,9,6,25,10,15,12
%N A074634 Cototient-remainder triangle: triangular array T(n,k) (n >= 1, 0 <= k < n) read by rows, where T(n,k) = smallest number x such that cototient(x) mod n = k.
%F A074634 Min{x; Mod[x-Phi[x], n]=r}, r=1..n, n=1, ...
%e A074634 1; 1,2; 1,2,4; 1,2,4,9; 1,2,4,9,6; 1,2,4,9,6,25; 1,2,4,9,6,18,10; 1,2,4,9,6,25,10,15; 1,2,4,9,6,25,10,15,12, ...
%t A074634 {k=0, s=0, fl=1}; Table[Print["#"]; Table[fl=1; Print[{r, m}]; Do[s=Mod[n-EulerPhi[n], m]; If[(s==r)&&(fl==1), Print[n]; fl=0], {n, 1, 500}], {r, 0, m-1}], {m, 1, 50}]
%Y A074634 Cf. A051953, A074625.
%K A074634 nonn,tabl
%O A074634 1,3
%A A074634 _Labos Elemer_, Aug 29 2002
%E A074634 Name modified to match data by _Sean A. Irvine_, Jan 22 2025