login
This site is supported by donations to The OEIS Foundation.

 

Logo

Annual Appeal: Please make a donation (tax deductible in USA) to keep the OEIS running. Over 5000 articles have referenced us, often saying "we discovered this result with the help of the OEIS".

Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A207639 Squares that can be written as a sum of 3 distinct nonzero squares in more than one way. 2
225, 361, 441, 529, 625, 729, 841, 900, 961, 1089, 1225, 1369, 1444, 1521, 1681, 1764, 1849, 2025, 2116, 2209, 2401, 2500, 2601, 2809, 2916, 3025, 3249, 3364, 3481, 3600, 3721, 3844, 3969, 4225, 4356, 4489, 4761, 4900, 5041, 5329, 5476, 5625, 5776, 5929 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

LINKS

Table of n, a(n) for n=1..44.

MATHEMATICA

t = Sort[Select[Flatten[Table[x^2 + y^2 + z^2, {x, 400}, {y, x + 1, 400}, {z, y + 1, 400}]], # < 160006 && IntegerQ[Sqrt[#]] &]];

f1[l_] := Module[{t = {}}, Do[If[l[[n]] != l[[n + 1]] && l[[n]] != l[[n - 1]], AppendTo[t, l[[n]]]], {n, Length[l] - 1}]; t];

s1 = Join[{First[t]}, f1[t]];

Complement[t, s1]

CROSSREFS

Sequence in context: A247885 A044871 A202005 * A077347 A207640 A267892

Adjacent sequences:  A207636 A207637 A207638 * A207640 A207641 A207642

KEYWORD

nonn

AUTHOR

Vladimir Joseph Stephan Orlovsky, Feb 19 2012

STATUS

approved

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

License Agreements, Terms of Use, Privacy Policy .

Last modified December 7 14:52 EST 2016. Contains 278877 sequences.