Найти сумму ряда

uses crt;
var n,i:integer;
    a,s,p:real;
begin
write('a=');
read(a);
write('n=');
read(n);
if a=0 then write('Ñóììà íå îïðåäåëåíà')
else
 begin
  s:=0;
  p:=1;
  for i:=1 to n do
   begin
    p:=p*a;
    s:=s+1/p
   end;
  write('s=',s:0:3)
 end;
end.

uses crt;
var n,i:integer;
    a,s,p:real;
begin
write('a=');
read(a);
write('n=');
read(n);
if a=0 then write('Ñóììà íå îïðåäåëåíà')
else
 begin
  p:=1/a;
  s:=p;
  for i:=2 to n do
   begin
    p:=p/(a*a);
    s:=s+p
   end;
  write('s=',s:0:3)
 end;
end.

uses crt;
var n,i:integer;
    s,s1:real;
begin
write('n=');
read(n);
s1:=0;
s:=0;
for i:=1 to n do
 begin
  s1:=s1+sin(i);
  s:=s+cos(i)/s1
 end;
write('s=',s:0:3)
end.

uses crt;
var n,i,z:integer;
    s,s1,s2:real;
begin
write('n=');
read(n);
s1:=0;
s:=0;
z:=1;
for i:=1 to n do
 begin
  z:=-z;
  s1:=s1+cos(i);
  s2:=s2+sin(i);
  s:=s+z*s1/s2
 end;
write('s=',s:0:3)
end.

uses crt;
var n,i:integer;
    a,s:real;
begin
write('a=');
read(a);
repeat
write('Íå÷åòíîå n=');
read(n);
until odd(n);
s:=0;
for i:=1 to n do
 begin
  if odd(i) then s:=s+cos(i*a)
  else s:=s+sin(i*a)
 end;
write('s=',s:0:3)
end.

uses crt;
var n,i:integer;
    s:real;
begin
write('n=');
read(n);
s:=sqrt(2*n);
for i:=n-1 downto 1 do
s:=sqrt(2*(i-1)+s);
write('s=',s:0:3)
end.