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First differences of A145646.
2

%I #21 Feb 01 2022 00:43:54

%S 2734,4556,6379,8202,10024,11846,13669,15492,17314,19136,20959,22782,

%T 24604

%N First differences of A145646.

%C Essentially (rounding effects ignored) 2*n+1 divided by the scaled constant A081821.

%F Conjectures from _Colin Barker_, May 08 2019: (Start)

%F G.f.: x*(2734 - 912*x + 2735*x^2 - 912*x^3) / ((1 - x)^2*(1 + x^2)).

%F a(n) = (3646 + (-i)^n + i^n + 7290*n) / 4 where i = sqrt(-1).

%F a(n) = 2*a(n-1) - 2*a(n-2) + 2*a(n-3) - a(n-4) for n>4.

%F (End)

%Y Cf. A081821, A145646.

%K nonn,easy,less

%O 1,1

%A _Paul Curtz_, Oct 15 2008

%E Edited by _N. J. A. Sloane_, Oct 15 2008 and _R. J. Mathar_, Oct 17 2008

%E Deleted keyword more: we do not want more terms of this ill-defined sequence. - _R. J. Mathar_, May 12 2019