%I A100402
%S A100402 1,4,7,1,4,7,1,4,7,1,4,7,1,4,7,1,4,7,1,4,7,1,4,7,1,4,7,1,4,7,1,4,7,1,4,
%T A100402 7,1,4,7,1,4,7,1,4,7,1,4,7,1,4,7,1,4,7,1,4,7,1,4,7,1,4,7,1,4,7,1,4,7,1,
%U A100402 4,7,1,4,7,1,4,7,1,4,7,1,4,7,1,4,7,1,4,7,1,4,7,1,4,7,1,4,7,1,4,7,1,4,7
%N A100402 Digital root of 4^n.
%C A100402 Equals A141725 (1, 13, 61, 253, 1021, 4093, 16381, ...) mod 9 . - Paul 
               Curtz (bpcrtz(AT)free.fr), Sep 15 2008
%C A100402 4^n mod 9. [From Zerinvary Lajos (zerinvarylajos(AT)yahoo.com), Nov 25 
               2009]
%e A100402 4^2 = 16, droot(16) = 7, the third entry.
%o A100402 (PARI) f(n,m) = for(x=0,n,print1(droot(m^x)",")) droot(n) = \ the digital 
               root of a number. { local(x); x= n%9; if(x>0,return(x),return(9)) 
               }
%o A100402 (Other) sage: [power_mod(4, n, 9)for n in xrange(0, 105)] # [From Zerinvary 
               Lajos (zerinvarylajos(AT)yahoo.com), Nov 25 2009]
%Y A100402 Sequence in context: A123734 A011519 A131594 this_sequence A135004 A086234 
               A016490
%Y A100402 Adjacent sequences: A100399 A100400 A100401 this_sequence A100403 A100404 
               A100405
%K A100402 easy,nonn,new
%O A100402 0,2
%A A100402 Cino Hilliard (hillcino368(AT)gmail.com), Dec 31 2004