A090635 - OEIS

%I #11 Nov 29 2019 20:47:43

%S 63,51,20,24,44,48,112,240,608,1552,3120,8144,16304,32624,65264,

%T 130544,264928,678448,1356912,4979232,19424016,58272480,226593936,

%U 763164288,3467499840,16339520448,65370077568,295266178368,1223245608192,6931725175296,40582548986112

%N Trajectory of 63 under the map k -> A003415(k) (taking the arithmetic derivative).

%D A. M. Gleason et al., The William Lowell Putnam Mathematical Competition: Problems and Solutions 1938-1964, Math. Assoc. America, 1980, p. 295.

%F 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 (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 Cf. A003415, A090636, A090637.

%K nonn

%O 1,1

%A _N. J. A. Sloane_, Dec 14 2003

%E More explicit name from _M. F. Hasler_, Nov 27 2019