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%I #6 May 15 2017 03:07:08
%S 0,1,3,7,12,18,26,35,45,58,72,87,104,122,141,162,184,207,233,260,288,
%T 318,349,381,415,450,486,526,567,609,653,698,744,792,841,891,944,998,
%U 1053,1110,1168
%N Partial sums of A004128.
%H G. C. Greubel, <a href="/A122250/b122250.txt">Table of n, a(n) for n = 0..1000</a>
%F G.f.: (1/(1-x))*Sum{k=0..infinity} ( x^(3^k)/((1-x)*(1-x^(3^k))) ).
%F a(n) = Sum_{j=0..n} ( Sum_{k=0..j} floor(j/3^k) ).
%t Table[Sum[Sum[Floor[3*j/3^k], {k, 1, j}], {j, 0, n}], {n, 0, 50}] (* _G. C. Greubel_, May 14 2017 *)
%o (PARI) for(n=0,50, print1(sum(j=0,n, sum(k=0,j, floor(j/3^k))), ", ")) \\ _G. C. Greubel_, May 14 2017
%K easy,nonn
%O 0,3
%A _Paul Barry_, Aug 27 2006
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