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 A366419 #25 Nov 16 2023 05:40:58 %S A366419 1,5,15,11,65,21,133,34,135,75,561,63,949,192,975,129,1921,165,3097, %T A366419 99,525,663,6095,231,1625,741,1215,576,8149,525,12121,513,8415,2091, %U A366419 8645,495,21349,3081,2535,363,34481,315,32551,1989,8775,5316,51935,903,6517,1875,28815,1062 %N A366419 Number of distinct integers of the form (x^n + y^n) mod n^3. %C A366419 It is enough to take x,y from {0,1,...,n^2-1}. %C A366419 It appears that the number of distinct integers of the form x^(p^k) + y^(p^k) mod (p^k)^m for a prime p>2 and natural k is A121278(p)*p^(k-1)*p^(k*(m-2)) for m>1. For m=1 see A366418. %C A366419 It appears that the number of distinct integers of the form x^n + y^n mod n^m for an odd n, m>1 is A121278(n)*n^(m-2). %o A366419 (PARI) a(n) = #setbinop((x, y)->Mod(x, n^3)^n+Mod(y, n^3)^n, [0..n^2-1]); \\ _Michel Marcus_, Oct 14 2023 %o A366419 (Python) %o A366419 def A366419(n): %o A366419 m = n**3 %o A366419 return len({(pow(x,n,m)+pow(y,n,m))%m for x in range(n**2) for y in range(x+1)}) # _Chai Wah Wu_, Nov 13 2023 %Y A366419 Cf. A366418, A121278, A366420, A365100. %K A366419 nonn %O A366419 1,2 %A A366419 _Albert Mukovskiy_, Oct 11 2023