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Forward difference of difference between 2^n and the next smaller power of 3.
1

%I #11 Oct 12 2019 18:51:24

%S 1,0,4,2,-2,32,10,-34,256,26,1024,590,-278,8192,3262,-6598,65536,

%T 12974,262144,169994,-14306,2097152,1005658,-1177330,16777216,4856618,

%U -18984578,134217728,10155130,536870912,298900846,-177039286,4294967296,1616365790,-3740837222

%N Forward difference of difference between 2^n and the next smaller power of 3.

%C a(n) is even for n >= 1.

%H Alois P. Heinz, <a href="/A328334/b328334.txt">Table of n, a(n) for n = 0..3323</a>

%F a(n) = A063005(n+1) - A063005(n).

%p b:= proc(n) option remember; (t-> t-3^ilog[3](t))(2^n) end:

%p a:= n-> b(n+1)-b(n):

%p seq(a(n), n=0..40);

%Y Cf. A063005.

%K sign

%O 0,3

%A _Alois P. Heinz_, Oct 12 2019