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Frobenius numbers: Difference between revisions
m
→{{header|REXX}}: changed some comments, simplified some code.
Not a robot (talk | contribs) (Add J) |
m (→{{header|REXX}}: changed some comments, simplified some code.) |
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if cols>0 then say ' index │'center(@Frob, 1 + cols*(w+1) )
if cols>0 then say '───────┼'center("" , 1 + cols*(w+1), '─')
do j=1; jp= j+1; y= @.j*@.jp - @.j - @.jp /*calculate a Frobenius number. */
▲ if cols==0 then iterate /*Build the list (to be shown later)? */
c= commas(y) /*maybe add commas to the number. */
$= $ right(c, max(w, length(c) ) ) /*add a Frobenius #──►list, allow big #*/
if j//cols\==0
say center(idx, 7)'│' substr($, 2); $= /*display what we have so far (cols). */
idx= idx + cols /*bump the index count for the output*/
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if $\=='' then say center(idx, 7)"│" substr($, 2) /*possible display residual output.*/
if cols>0 then say '───────┴'center("" , 1 + cols*(w+1), '─')
say
say 'Found ' commas(j-1) @FROB
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commas: parse arg ?; do jc=length(?)-3 to 1 by -3; ?=insert(',', ?, jc); end; return ?
/*──────────────────────────────────────────────────────────────────────────────────────*/
genP: @.1=2; @.2=3; @.3=5; @.4=7; @.5=11; @.6=
#=
/* [↓] generate more primes ≤ high.*/
do j=@.#+
parse var j '' -1 _; if _==5 then iterate /*J divisible by 5?
if j// 3==0 then iterate /*" " " 3?
if j// 7==0 then iterate /*" " " 7?
if j//11==0 then iterate /*" " " 11?
do k=6 while s.k<=j /* [↓] divide by the known odd primes.*/
if j // @.k == 0 then iterate j /*Is J ÷ X? Then not prime. ___ */
end /*k*/ /* [↑] only process numbers ≤ √ J */
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11 │ 1,079 1,439 1,679 1,931 2,391 3,015 3,479 3,959 4,619 5,039
21 │ 5,615 6,395 7,215 8,447 9,599
───────┴───────────────────────────────────────────────────────────────────────────────────────────────────────────────
Found 25 Frobenius numbers that are < 10,000
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