login
The OEIS is supported by the many generous donors to the OEIS Foundation.

 

Logo
Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A018850 Numbers that are the sum of 2 cubes in more than 1 way (primitive solutions). 4

%I #33 Jul 27 2020 04:51:20

%S 1729,4104,20683,39312,40033,64232,65728,134379,149389,171288,195841,

%T 216027,327763,402597,439101,443889,515375,684019,704977,805688,

%U 842751,920673,955016,984067,994688,1009736,1016496,1073375,1092728,1331064

%N Numbers that are the sum of 2 cubes in more than 1 way (primitive solutions).

%C Nakao's table has more entries because he lists nonprimitive numbers if they are the sum of two cubes in three ways.

%C _Rajesh Bhowmick_, Dec 12 2011: The odd number 40533595075161 can be represented as sum of two cubes in just two different ways: (34314)^(3)+(5073)^(3) = (34321)^(3)+(4730)^(3). Here, the cubes are greater than 1, there is no common factor between the odd numbers, there is no common factor between the L.H.S & the R.H.S, the even number is greater than 2, the cubes are in their primitive form, and they are not of the form (27)^(3) or (121)^(3) (which are actually (3)^(9) & (11)^(6)).

%H Shahar Amitai, <a href="/A018850/b018850.txt">Table of n, a(n) for n = 1..9859</a> (terms a(1)-a(1694) from T. D. Noe).

%H Shahar Amitai, <a href="/A018850/a018850.txt">Python code to generate all primitive taxicab numbers up to N.</a>

%H H. Nakao, <a href="http://www.kaynet.or.jp/~kay/misc/log/rtaxi.log">Ramanujan Taxi Numbers [1...1000000000]</a>

%H Eric Weisstein's World of Mathematics, <a href="http://mathworld.wolfram.com/CubicNumber.html">Cubic Number</a>

%Y Cf. A001235.

%K nonn

%O 1,1

%A _David W. Wilson_

Lookup | Welcome | Wiki | Register | Music | Plot 2 | Demos | Index | Browse | More | WebCam
Contribute new seq. or comment | Format | Style Sheet | Transforms | Superseeker | Recents
The OEIS Community | Maintained by The OEIS Foundation Inc.

License Agreements, Terms of Use, Privacy Policy. .

Last modified March 29 09:32 EDT 2024. Contains 371268 sequences. (Running on oeis4.)