#OK to post homework 
#Natalya Ter-Saakov, April 10, Assignment 21
read "C21.txt":

#Problem 1

#JTseq(N): The first N terms of the sequence of congruent numbers, those that are areas of right-angled triangle
#with rational sides. Shuold be called the Tunnell numbers
JTseq:=proc(N) local n,La,Lb,L:
with(NumberTheory):
La:=aSeq(N):
Lb:=bSeq(N):
L:=[]:
for n from 2 to N do
	if IsSquareFree(n) then 
	if n mod 2 = 1 and La[n]=0 then
		L:=[op(L),n]:
	fi:
	if n mod 2 = 0 and Lb[n/2]=0 then
		L:=[op(L),n]:
	fi:
	fi:
od:
L:   
end:

#Problem 2
#JTseqW(N): All the terms <=N of the sequence of congruent numbers, those that are areas of right-angled triangle
#with rational sides. Shuold be called the Tunnell numbers; Using the Wikipedia version
JTseqW:=proc(N) local n,L:
L:=[]:
for n from 1 to N do
 
if IsCon(n) and IsSquareFree(n) then
   L:=[op(L),n]:
  fi:
od:
L:
end: