Arithmetic numbers: Difference between revisions

using prime decomposition is lengthy, but much faster.<br>

Change last lines of [[Factors_of_an_integer#using_Prime_decomposition]] even more.

[[Factors_of_an_integer#using_Prime_decomposition]] added function and change main routine.

<lang pascal>

const

//make size of sieve using 11 MB of 16MB Level III cache

SizePrDeFe = 192*1024;

.....

function IsArithmetic(const PrimeFact:tPrimeFac):boolean;inline;

begin

with PrimeFact do

IsArithmetic := pfSumOfDivs mod pfDivCnt = 0;

end;

var

pPrimeDecomp :tpPrimeFac;

T0:Int64;

n,lmt,cnt,primeCnt : NativeUInt;

Begin

InitSmallPrimes;

T0 := GetTickCount64;

cnt := 1;

primeCnt := 1;

lmt := 10;

n := 2;

Init_Sieve(n);

repeat

pPrimeDecomp:= GetNextPrimeDecomp;

if IsArithmetic(pPrimeDecomp^) then

begin

inc(cnt);

if pPrimeDecomp^.pfDivCnt = 2 then

inc(primeCnt);

end;

if cnt = lmt then

begin

writeln(lmt:14,n:14,lmt-primeCnt:14);

lmt := lmt*10;

end;

inc(n);

until lmt>1000*1000*1000;

T0 := GetTickCount64-T0;

writeln;

end.</lang>

{{out|@Home AMD 5600G}}

<pre>

10 17 3

100 149 65

1000 1361 782

10000 12953 8458

100000 125587 88219

1000000 1228663 905043

10000000 12088243 9206547

100000000 119360473 93192812

1000000000 1181451167 940432725

20.78user 0.00 system 0:20.79 elapsed 99%CPU </pre>