%I A051638
%S A051638 1,2,4,2,4,8,4,8,13,2,4,8,4,8,16,8,16,26,4,8,13,8,16,26,13,26,40,
%T A051638 2,4,8,4,8,16,8,16,26,4,8,16,8,16,32,16,32,52,8,16,26,16,32,52,
%U A051638 26,52,80,4,8,13,8,16,26,13,26,40,8,16,26,16,32,52,26,52,80,13
%N A051638 Sum_{k=0..n} (C(n,k) mod 3).
%H A051638 Michael Gilleland, <a href="selfsimilar.html">Some Self-Similar Integer 
               Sequences</a>
%H A051638 A. Granville, <a href="http://www.dms.umontreal.ca/~andrew/Binomial/intro.html">
               Binomials modulo a prime</a>
%F A051638 Write n in base 3; if the representation contains r 1's and s 2's then 
               a(n) = 2^{r-1} * (3^(s+1) - 1) = 1/2 * (3*A006047(n) - 2^(A062756(n))). 
               - Robin Chapman (rjc(AT)MATHS.EX.AC.UK), Ahmed Fares (ahmedfares(AT)my-deja.com) 
               and others, Jul 16, 2001
%Y A051638 Cf. A001316.
%Y A051638 Sequence in context: A112791 A143107 A166242 this_sequence A155682 A151706 
               A055372
%Y A051638 Adjacent sequences: A051635 A051636 A051637 this_sequence A051639 A051640 
               A051641
%K A051638 nonn
%O A051638 0,2
%A A051638 N. J. A. Sloane (njas(AT)research.att.com).