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 A272935 #23 May 24 2016 09:39:08 %S A272935 1729,20683,149389,195841,327763,2418271,6058747,7620661,9443761, %T A272935 10765603,13623913,18406603,32114143,68007673,105997327,106243219, %U A272935 166560193,216226981,446686147,584504191,813357253,959281759,1098597061,1736913439,2072769211,2460483307 %N A272935 Taxi-cab numbers (A001235) that are the product of exactly three (not necessarily distinct) primes. %C A272935 Note that the sum of two positive cubes cannot be prime except 2, obviously. Additionally, if the sum of two positive cubes is a semiprime, then, all corresponding semiprimes have a unique representation as a sum of two distinct positive cubes (see comment section of A085366). Since we know that 1729 is the first member of A001235 and it has three prime divisors, the minimum value of the number of prime divisors of a taxi-cab number must be three. This was the motivation of the definition of this sequence. %H A272935 Chai Wah Wu, <a href="/A272935/b272935.txt">Table of n, a(n) for n = 1..131</a> %e A272935 Taxi-cab number 1729 is a term because 1729 = 7*13*19. %e A272935 Taxi-cab number 20683 is a term because 20683 = 13*37*43. %e A272935 Taxi-cab number 149389 is a term because 149389 = 31*61*79. %Y A272935 Cf. A001235, A003325, A014612, A085366. %K A272935 nonn %O A272935 1,1 %A A272935 _Altug Alkan_, May 11 2016 %E A272935 a(7)-a(26) from _Chai Wah Wu_, May 22 2016