cp's OEIS Frontend

A176304 a(n) = (-1)^n * n * a(n-1) - 1, with a(0)=0.

%I A176304 #10 Sep 08 2022 08:45:52
%S A176304 0,-1,-3,8,31,-156,-937,6558,52463,-472168,-4721681,51938490,
%T A176304 623261879,-8102404428,-113433661993,1701504929894,27224078878303,
%U A176304 -462809340931152,-8330568136760737,158280794598454002
%N A176304 a(n) = (-1)^n * n * a(n-1) - 1, with a(0)=0.
%C A176304 The sequence alternates in the sign and in the odd-even parity.
%H A176304 G. C. Greubel, <a href="/A176304/b176304.txt">Table of n, a(n) for n = 0..445</a>
%p A176304 a(n):=`if`(n=0, 0, (-1)^n*n*a(n-1) -1); seq(a(n), n=0..20); # _G. C. Greubel_, Nov 26 2019
%t A176304 a[n_]:= a[n] = If[n==0, 0, (-1)^n*n*a[n-1] -1]; Table[a[n], {n, 0, 20}]
%o A176304 (PARI) a(n) = if(n==0, 0, (-1)^n*n*a(n-1) -1); \\ _G. C. Greubel_, Nov 26 2019
%o A176304 (Magma)
%o A176304 function a(n)
%o A176304   if n eq 0 then return 0;
%o A176304   else return (-1)^n*n*a(n-1) -1;
%o A176304   end if; return a; end function;
%o A176304 [a(n): n in [0..20]]; // _G. C. Greubel_, Nov 26 2019
%o A176304 (Sage)
%o A176304 @CachedFunction
%o A176304 def a(n):
%o A176304     if (n==0): return 0
%o A176304     else: return (-1)^n*n*a(n-1) -1
%o A176304 [a(n) for n in (0..20)] # _G. C. Greubel_, Nov 26 2019
%K A176304 sign,easy
%O A176304 0,3
%A A176304 _Roger L. Bagula_, Apr 14 2010