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 A090635 #11 Nov 29 2019 20:47:43
%S A090635 63,51,20,24,44,48,112,240,608,1552,3120,8144,16304,32624,65264,
%T A090635 130544,264928,678448,1356912,4979232,19424016,58272480,226593936,
%U A090635 763164288,3467499840,16339520448,65370077568,295266178368,1223245608192,6931725175296,40582548986112
%N A090635 Trajectory of 63 under the map k -> A003415(k) (taking the arithmetic derivative).
%D A090635 A. M. Gleason et al., The William Lowell Putnam Mathematical Competition: Problems and Solutions 1938-1964, Math. Assoc. America, 1980, p. 295.
%F A090635 a(n+1) = A003415(a(n)), a(1) = 63. a(n) = 4*A129286(n-3) for n > 2. - _M. F. Hasler_, Nov 27 2019
%o A090635 (PARI) A090635(n, a=63)={if(n<0, vector(-n, n, if(n>1, a=A003415(a), a)), for(n=2, n, a=A003415(a)); a)} \\ For n<0 return the vector a[1..-n]. - _M. F. Hasler_, Nov 27 2019
%Y A090635 Cf. A003415, A090636, A090637.
%K A090635 nonn
%O A090635 1,1
%A A090635 _N. J. A. Sloane_, Dec 14 2003
%E A090635 More explicit name from _M. F. Hasler_, Nov 27 2019