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%I #9 May 01 2013 21:13:43
%S 8,9,8,1,8,1,8,1,8,8,1,1,8,1,8,8,8,1,1,8,1,1,8,8,1,8,1,8,1,8,1,8,8,1,
%T 8,1,1,1,8,8,8,1,8,1,8,1,1,1,8,1,8,8,1,8,8,8,8,1,1,8,1,8,1,8,1,8,1,1,
%U 8,1,8,8,1,1,1,8,8,1,8,1,8,1,8,1,1,8,8,1,8,1,8,8,1,8,1,8,8,8,1,1
%N Digital root (cf. A010888) of prime(n)^3.
%C Apart from a(2)=9 all other terms are either 1 or 8.
%e a(3)=8 because p(3)=5 and 5^3=125 -> sum-of-digits = 8. a(4)=1 because p(3)=7 and 7^3=343 -> sum-of-digits = 10 -> sum-of-digits = 1.
%t n=3; su[x_] := Sum[IntegerDigits[x][[i]], {i, Length[IntegerDigits[x]]}]; Table[su[su[su[su[Prime[x]^n]]]], {x, 100}]
%t Table[If[(m9=Mod[Prime[n]^3,9])==0,9,m9],{n,200}]
%Y Cf. A010888, A021596, A056992, A010888, A038194, A166923.
%K nonn,base
%O 1,1
%A _Zak Seidov_, Sep 01 2002, Oct 23 2009
%E Edited by _N. J. A. Sloane_, Oct 29 2009