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A140048 a(n) = (1/2)*Sum_{j=0..2^n-1} j^(n-1) for n>=1. 1

%I

%S 1,3,70,7200,3098760,5461682688,39119789090720,1134989202339225600,

%T 133147573896710665570432,63073498348368958240316325888,

%U 120514654247860687784734309977868800

%N a(n) = (1/2)*Sum_{j=0..2^n-1} j^(n-1) for n>=1.

%C Related to the Prouhet-Tarry-Escott problem.

%F Main diagonal of triangle A140047.

%F a(n) = Sum_{j=0..2^n-1, A010060(j)=0 } j^(n-1), n>=1; also,

%F a(n) = Sum_{j=0..2^n-1, A010060(j)=1 } j^(n-1), n>=1;

%F where A010060 is the Thue-Morse sequence.

%e For n=3, since A010060(j) = 0 at j={0,3,5,6}, then

%e a(3) = 0^2 + 3^2 + 5^2 + 6^2 = 70 ;

%e and since A010060(j) = 1 at j={1,2,4,7}, we also have

%e a(3) = 1^2 + 2^2 + 4^2 + 7^2 = 70.

%e For n=4, since A010060(j) = 0 at j={0,3,5,6,9,10,12,15}, then

%e a(4) = 0^3 + 3^3 + 5^3 + 6^3 + 9^3 + 10^3 + 12^3 + 15^3 = 7200 ;

%e and since A010060(j) = 1 at j={1,2,4,7,8,11,13,14}, we also have

%e a(4) = 1^3 + 2^3 + 4^3 + 7^3 + 8^3 + 11^3 + 13^3 + 14^3 = 7200.

%o (PARI) a(n)=sum(j=0,2^n-1,j^(n-1))/2

%Y Cf. A140047; A010060.

%K nonn

%O 1,2

%A _Paul D. Hanna_, May 12 2008

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Last modified February 9 06:46 EST 2023. Contains 360153 sequences. (Running on oeis4.)