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A079624 a(1) = a(2) = 1, a(3) = 6, a(n) = abs(a(n-1) - a(n-2) - a(n-3)).

%I A079624 #13 Sep 11 2024 10:08:39
%S A079624 1,1,6,4,3,7,0,10,3,7,6,4,9,1,12,2,11,3,10,4,9,5,8,6,7,7,6,8,5,9,4,10,
%T A079624 3,11,2,12,1,13,0,14,1,13,2,12,3,11,4,10,5,9,6,8,7,7,8,6,9,5,10,4,11,
%U A079624 3,12,2,13,1,14,0,15,1,14,2,13,3,12,4,11,5,10,6,9,7,8,8,7,9,6,10,5,11,4,12,3
%N A079624 a(1) = a(2) = 1, a(3) = 6, a(n) = abs(a(n-1) - a(n-2) - a(n-3)).
%H A079624 Reinhard Zumkeller, <a href="/A079624/b079624.txt">Table of n, a(n) for n = 1..10000</a>
%F A079624 For n >= 5, a(n^2 + 24*n - 13) = 0.
%F A079624 For n >= 38, Max( a(k) : 1<=k<=n) = floor(sqrt(n+156)).
%t A079624 a[n_]:= a[n]= If[n<4, 6^Floor[(n-1)/2], Abs[a[n-1] -a[n-2] -a[n-3]]];
%t A079624 Table[a[n], {n,100}] (* _G. C. Greubel_, Sep 11 2024 *)
%o A079624 (Haskell)
%o A079624 a079624 n = a079624_list !! (n-1)
%o A079624 a079624_list = 1 : 1 : 6 : zipWith3 (\u v w -> abs (w - v - u))
%o A079624                a079624_list (tail a079624_list) (drop 2 a079624_list)
%o A079624 -- _Reinhard Zumkeller_, Oct 11 2014
%o A079624 (Magma)
%o A079624 m:=120;
%o A079624 A079624:=[n le 3 select 6^Floor((n-1)/2) else Abs(Self(n-1) - Self(n-2) - Self(n-3)): n in [1..m+5]];
%o A079624 [A079624[n]: n in [1..m]]; // _G. C. Greubel_, Sep 11 2024
%o A079624 (SageMath)
%o A079624 @CachedFunction
%o A079624 def a(n): # a = A079624
%o A079624     if n<4: return 6^((n-1)//2)
%o A079624     else: return abs(a(n-1)-a(n-2)-a(n-3))
%o A079624 [a(n) for n in range(1,101)] # _G. C. Greubel_, Sep 11 2024
%Y A079624 Cf. A077623, A077653, A078108, A079623, A080096, A088226.
%K A079624 nonn
%O A079624 1,3
%A A079624 _Benoit Cloitre_, Jan 30 2003