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a(1) = a(2) = 1; a(n) = (a(n-1) + a(n-2)) mod (n - a(n-1)).
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%I #20 Mar 14 2020 18:51:43

%S 1,1,0,1,1,2,3,0,3,3,6,3,9,2,11,3,0,3,3,6,9,2,11,0,11,11,6,17,11,9,20,

%T 5,25,3,28,7,5,12,17,6,23,10,0,10,10,20,3,23,0,23,23,17,4,21,25,15,40,

%U 1,41,4,45,15,12,27,1,28,29,18,47,19,14,33,7,40

%N a(1) = a(2) = 1; a(n) = (a(n-1) + a(n-2)) mod (n - a(n-1)).

%C Performing the modulus operation, the smallest nonnegative residue is to be taken.

%C a(A226483(n)) = n and a(m) <> n for m < A226483(n). - _Reinhard Zumkeller_, Jun 09 2013

%H Reinhard Zumkeller, <a href="/A224909/b224909.txt">Table of n, a(n) for n = 1..10000</a>

%e a(8) = (a(7) + a(6)) mod (8 - a(7)) = (2+3) mod (8-3) = 5 mod 5 = 0.

%t a[1]=1; a[2]=1; a[n_] := a[n] = Mod[a[n-1] + a[n-2], n - a[n-1]]; Array[a, 74] (* _Giovanni Resta_, Jun 08 2013 *)

%t nxt[{n_, a_, b_}] := {n + 1, b, Mod[a + b, n + 1 - b]}; NestList[nxt,{2,1,1},80][[All,2]] (* _Harvey P. Dale_, Mar 14 2020 *)

%o (Haskell)

%o a224909 n = a224909_list !! (n-1)

%o a224909_list = 1 : 1 : zipWith mod

%o (zipWith (+) a224909_list $ tail a224909_list)

%o (zipWith (-) [3..] $ tail a224909_list)

%o -- _Reinhard Zumkeller_, Jun 09 2013

%K nonn

%O 1,6

%A _David S. Newman_, Apr 19 2013

%E a(31)-a(74) from _Giovanni Resta_, Jun 08 2013