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%I #32 Feb 19 2024 10:28:50
%S 0,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,
%T -1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,
%U -1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1
%N Sign(-n): a(n) = 1 if -n > 0, = -1 if -n < 0, = 0 if n = 0.
%H <a href="/index/Rec#order_01">Index entries for linear recurrences with constant coefficients</a>, signature (1).
%F G.f.: A(x) = -x/(1-x).
%F a(n) = -A057427(n).
%F Series reversion of g.f. A(x) is A(A(x)). - _Nikolaos Pantelidis_, Apr 13 2022
%t Table[Sign[-n], {n, 0, 80}] (* _Arkadiusz Wesolowski_, Sep 16 2012 *)
%o (PARI) a(n) = sign(-n); \\ _Michel Marcus_, Apr 13 2022
%Y First differences of A001489.
%Y Cf. A057427.
%K easy,sign
%O 0,1
%A _Henry Bottomley_, Sep 05 2000