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 A121980 #3 Mar 30 2012 17:39:13 %S A121980 1,3,4,8,13,24,27,28,32,49,64,81,98,104,108,125,147,168,181,189,192, %T A121980 216,224,228,256,312,343,351,361,375,388,392,500,507,512,525,549,588, %U A121980 648,671,676,729,756,784,832,847,864,1000,1014,1029,1176,1183,1225,1261 %N A121980 Positive integers z, without duplication, in x^3+y^3=z^2. %C A121980 The first duplicate is (-23,71,588),(14,70,588), the second (-119,140,1029),(49,98,1029). A033430(m) and A000578(k) are subsets since (x,y,z)=(2m,2m,4m^3) or (x,y,z)=(0,k^2,k^3) solve x^3+y^3=z^2. The "leakage" problem of A103254 can be avoided by introducing s=x+y and d=y-x and searching for solutions of the transformed equation s(s^2+3d^2)=4z^2 over all positive divisors s of 4z^2. %e A121980 (x,y,z)=(0,1,1),(1,2,3),(2,2,4),(0,4,8),(-7,8,13),(4,8,24),(0,9,27),(-6,10,28), %e A121980 (8,8,32),(-7,14,49),(0,16,64),(9,18,81),(7,21,98),(-28,32,104). %Y A121980 Cf. A103254, A103255. %K A121980 nonn %O A121980 1,2 %A A121980 _R. J. Mathar_, Sep 11 2006