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 A369768 #20 Feb 17 2024 11:28:08 %S A369768 3,9,21,27,71,81,195,233,243,711,729,1583,1749,2157,2187,6561,14829, %T A369768 15747,19629,19683,57609,59049,141717,154727,175537,177147,385559, %U A369768 394471,414649,422729,446489,462601,468919,482759,488431,504161,515649,524559,529599,530529 %N A369768 Numbers X such that X^2 + Y^2 = 3^(2*k) + 1 and X > Y > 0 and k is the ternary digit length of X-1. %C A369768 The number of terms for a given k is A025435(3^(2*k)+1). %H A369768 A.H.M. Smeets, <a href="/A369768/b369768.txt">Table of n, a(n) for n = 1..191</a> %Y A369768 Cf. A004018, A025435. %Y A369768 Cf. A369703 (base 2), this sequence (base 3), A369769 (base 5), A368418 (base 10). %K A369768 nonn,base %O A369768 1,1 %A A369768 _A.H.M. Smeets_, Jan 31 2024