This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.
%I A377231 #55 Dec 09 2024 11:01:08
%S A377231 1,2,2,4,8,5,4,2,8,7,2,5,1,5,5,7,8,2,7,5,8,4,5,2,1,2,2,4,8,5,4,2,8,7,
%T A377231 2,5,1,5,5,7,8,2,7,5,8,4,5,2,1,2,2,4,8,5,4,2,8,7,2,5,1,5,5,7,8,2,7,5,
%U A377231 8,4,5,2,1,2,2,4,8,5,4,2,8,7,2,5,1,5,5,7,8,2,7,5,8,4,5,2
%N A377231 a(n) = digital root of 2^Fibonacci(n).
%C A377231 This sequence has period 24.
%H A377231 <a href="/index/Rec#order_24">Index entries for linear recurrences with constant coefficients</a>, signature (0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,1).
%F A377231 a(n) = (a(n-1) * a(n-2) - 1) mod 9 + 1.
%F A377231 a(n) = A010888(A000301(n)).
%t A377231 Module[{a, n}, RecurrenceTable[{a[n] == Mod[a[n-1]*a[n-2] - 1, 9] + 1, a[0] == 1, a[1] == 2}, a, {n, 0, 99}]] (* or *)
%t A377231 PadRight[{}, 100, {1, 2, 2, 4, 8, 5, 4, 2, 8, 7, 2, 5, 1, 5, 5, 7, 8, 2, 7, 5, 8, 4, 5, 2}] (* _Paolo Xausa_, Nov 08 2024 *)
%Y A377231 Cf. A000301, A010888.
%K A377231 nonn,easy,base
%O A377231 0,2
%A A377231 _Robert Bruce Gray_, Oct 20 2024