This site is supported by donations to The OEIS Foundation. Hints (Greetings from The On-Line Encyclopedia of Integer Sequences!)
 A025342 Numbers that are the sum of 3 distinct nonzero squares in exactly 4 ways. 1

%I

%S 161,189,194,209,234,254,261,270,281,285,290,293,299,321,362,365,369,

%T 371,378,386,390,395,401,405,406,419,429,449,450,465,469,477,482,485,

%U 489,491,501,510,518,534,539,557,563,570,573,574,586,589,601,609,633,644,645,649

%N Numbers that are the sum of 3 distinct nonzero squares in exactly 4 ways.

%H Robert Israel, <a href="/A025342/b025342.txt">Table of n, a(n) for n = 1..3007</a>

%H <a href="/index/Su#ssq">Index entries for sequences related to sums of squares</a>

%p N:= 10^6;

%p A:= Vector(N):

%p for a from 1 to floor(sqrt(N/3)) do

%p for b from a+1 to floor(sqrt((N-a^2)/2)) do

%p c:= [\$(b+1) .. floor(sqrt(N-a^2-b^2))]:

%p v:= map(t -> a^2 + b^2 + t^2, c):

%p A[v]:= map(`+`,A[v],1)

%p od od:

%p select(t -> A[t]=4,[\$1..N]); # _Robert Israel_, Jan 03 2016

%t Sort[Transpose[Select[Tally[Total/@Subsets[Range^2,{3}]],#[]==4&]][]] (* _Harvey P. Dale_, Apr 24 2013 *)

%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 | Recent
The OEIS Community | Maintained by The OEIS Foundation Inc.

Last modified September 17 22:53 EDT 2019. Contains 327147 sequences. (Running on oeis4.)