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 A367484 #36 Jan 23 2024 14:15:24
%S A367484 1,3,7,19,55,165,493,1477,4429,13287,39859,119575,358723,1076169,
%T A367484 3228505,9685513,29056537
%N A367484 Number of integers of the form (x^4 + y^4) mod 3^n; a(n) = A289559(3^n).
%C A367484 It appears that for n > 4: a(n) = 2*3^(n-1) + a(n-4).
%C A367484 For n < 5: a(n) = 2*3^(n-1) + 1.
%C A367484 Conjecture in closed form: a(n) = 2*ceiling(3^(n+3)/80) - 1.
%F A367484 Conjecture: a(n) = 2*ceiling(3^(n+3)/80) - 1.
%F A367484 a(n) = A289559(3^n). - _Thomas Scheuerle_, Nov 20 2023
%o A367484 (PARI) a(n) = #setbinop((x, y)->Mod(x,3^n)^4+Mod(y,3^n)^4, [0..3^n-1]);
%o A367484 (Python)
%o A367484 def A367484(n):
%o A367484 m = 3**n
%o A367484 return len({(pow(x,4,m)+pow(y,4,m))%m for x in range(m) for y in range(x+1)}) # _Chai Wah Wu_, Jan 23 2024
%Y A367484 Subsequence of A289559.
%Y A367484 Cf. A000244, A039300, A046631, A155918.
%K A367484 nonn,more
%O A367484 0,2
%A A367484 _Albert Mukovskiy_, Nov 19 2023