Idoneal numbers: Difference between revisions
Added Algol W
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OD
END
</syntaxhighlight>
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<pre>
1 2 3 4 5 6 7 8 9 10 12 13 15
16 18 21 22 24 25 28 30 33 37 40 42 45
48 57 58 60 70 72 78 85 88 93 102 105 112
120 130 133 165 168 177 190 210 232 240 253 273 280
312 330 345 357 385 408 462 520 760 840 1320 1365 1848
</pre>
=={{header|ALGOL W}}==
<syntaxhighlight lang="algolw">
begin % find idoneal numbers - numbers that cannot be written as ab + bc + ac %
% where 0 < a < b < c %
% there are 65 known idoneal numbers %
integer count, MAX_COUNT, n;
MAX_COUNT := 65;
count := 0;
n := 0;
while count < MAX_COUNT do begin
logical idoneal;
integer a;
n := n + 1;
idoneal := true;
a := 1;
while ( a + 2 ) < n and idoneal do begin
integer b;
b := a + 1;
while begin
integer ab, sum;
ab := a * b;
sum := 0;
if ab < n then begin
integer c;
c := ( n - ab ) div ( a + b );
sum := ab + ( c * ( b + a ) );
if c > b and sum = n then idoneal := false;
b := b + 1
end if_ab_lt_n ;
sum <= n and idoneal and ab < n
end do begin end;
a := a + 1
end;
if idoneal then begin
count := count + 1;
writeon( i_w := 4, s_w := 0, " ", n );
if count rem 13 = 0 then write()
end if_idoneal
end while_count_lt_MAX_COUNT
end.
</syntaxhighlight>
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