Rare numbers: Difference between revisions

=={{header|Quackery}}==

Naive version.

Timings for Quackery running on PyPy3 on one core of a 3 GHz 6-Core Intel Core i5 Mac mini at 100%.

First result; less than a second. Second result; less than five minutes (possibly a lot less - I went to make a cup of tea), third result; more than twelve and less than fifteen hours. At this point I estimated from other timings on this page that getting the fourth and fifth results would take about a week and killed the process. :-(

On the other hand; code development time, less than five minutes. :-)

<lang Quackery>[ dup 1

[ 2dup > while

+ 1 >>

2dup / again ]

drop nip ] is sqrt ( n --> n )

[ dup sqrt 2 ** = not ] is !square ( n --> b )

[ number$ reverse

$->n drop ] is revnumber ( n --> n )

[ 0 swap

[ base share /mod

rot + swap

dup 0 = until ]

drop ] is digitalroot ( n --> n )

[ true swap

dup revnumber

2dup > not iff

[ 2drop not ] done

2dup + !square iff

[ 2drop not ] done

2dup - !square iff

[ 2drop not ] done

2drop ] is rare ( n --> b )

[ 0

[ 1+ dup rare if

[ dup echo cr

dip [ 1 - ] ]

over 0 = until ]

2drop ] is echorarenums ( n --> b )

5 echorarenums</lang>

{{Out}}

<pre>5

621770

281089082</pre>