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A106469 Expansion of (1+x^2)(1+2x)/(1-x^2). 1

%I

%S 1,2,2,4,2,4,2,4,2,4,2,4,2,4,2,4,2,4,2,4,2,4,2,4,2,4,2,4,2,4,2,4,2,4,

%T 2,4,2,4,2,4,2,4,2,4,2,4,2,4,2,4,2,4,2,4,2,4,2,4,2,4,2,4,2,4,2,4,2,4,

%U 2,4,2,4,2,4,2,4,2,4,2,4,2,4,2,4,2,4,2,4,2,4,2,4,2,4,2,4

%N Expansion of (1+x^2)(1+2x)/(1-x^2).

%C Row sums of number triangle A106468.

%F a(0)=1, a(n)=(2-0^((n-1)/2))(1-(-1)^n)+(2-0^(n/2))(1+(-1)^n)/2, n>1.

%K easy,nonn

%O 0,2

%A _Paul Barry_, May 03 2005

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Last modified November 13 12:45 EST 2019. Contains 329094 sequences. (Running on oeis4.)