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A071641 a(n) defined by recursion in the formula section.

%I A071641 #24 Jan 28 2022 11:13:59
%S A071641 1,1,1,1,3,7,9,3,7,3,7,3,5,7,7,7,9,8,7,5,7,7,3,3,9,3,3,1,7,7,3,8,8,3,
%T A071641 5,7,1,1,7,8,7,7,3,3,7,3,3,8,7,7,7,7,7,9,8,7,5,7,7,1,1,3,3,8,7,3,5,1,
%U A071641 3,8,5,3,5,3,1,7,1,3,7,7,9,7,9,3,3,7,7,7,7,3,7,3,9,5,9,7,3,7,8,5,9,7,9,5,5
%N A071641 a(n) defined by recursion in the formula section.
%C A071641 All terms are in {1, 3, 5, 7, 8, 9}.
%D A071641 Ivars Peterson, The Jungles of Randomness, 1998, John Wiley and Sons, Inc., page 207.
%F A071641 a(n) = 10 - (prime(g(n)) mod 10) with g(n) = 9 - (f(n) mod 9) and f(n) = f(n-1) + f(n-4) + floor((f(n-1) + f(n-4))/10) for n>= 4, f(n) = 1 for n<4.
%t A071641 f[0]=f[1]=f[2]=f[3]=1; f[x_] := f[x]=f[x-1]+f[x-4]+Floor[f[x-1]/10+f[x-4]/10];
%t A071641 g[x_] := g[x]=9-Mod[f[x], 9];
%t A071641 h[x_] := h[x]=10-Mod[Prime[g[x]], 10];
%t A071641 Table[h[n], {n, 0, 200}];
%Y A071641 Cf. A000040, A072003.
%K A071641 nonn,easy,less
%O A071641 0,5
%A A071641 _Roger L. Bagula_, Jun 22 2002
%E A071641 Edited by _Robert G. Wilson v_, Jun 25 2002
%E A071641 Edited by the Associate Editors of the OEIS, Jan 28 2022