# Talk:Ludic numbers

## 1 is the loneliest number...[edit]

The OEIS thinks the sequence starts at 1. Obviously the task as originally specified draws from a source that thinks you should skip the 1, perhaps by analogy with prime numbers, which might or might not be construed as a false analogy, since the sequence contains other non-primes like 25, and since this sieve is based on position, not on value, as primes are. I like it with the 1, and marked the Python entry as incorrect somewhat tongue-in-cheekly, but I think we can agree that we oughta agree on definition one way or the other before this becomes a real task. `:-)` --TimToady (talk) 21:41, 15 March 2014 (UTC)

- Thanks Tim, I was so focused on the sieve loop, I forgot the initial 1. --Paddy3118 (talk) 08:23, 16 March 2014 (UTC)

## Needs proper description[edit]

The OEIS wiki page's description of Ludic sequence generation is very clear, while that of the task page here is very much not. By the wording here, step 1 gives 2, 3, 4, ..., and L = 2; step 2 wants to "remove every L'th indexed item from the array (including the first)", which means what, remove 2 (the first), 3 (first L-th), 5 (second L-th), and so on? So are we left with 4, 6, 8... now? And what's the difference between "every L'th *indexed*" and, say, just "every L-th"?

Also, I believe the "th" suffix is more commonly typeset as "L-th" or "*L*th" (the italic "L" in the latter optional.) --Ledrug (talk) 08:40, 16 March 2014 (UTC)

## Task description generator[edit]

Somewhere to stash it. <lang python>from nth import nth

def _parray(array, indexed=None, nmax=25):

```
lst = array[:nmax]
return ('
``````
' +
( ('
```~~%i~~ ' % lst[0])
if indexed else
('%i ' % lst[0]) ) +
' '.join( (('%i' % l)
if not indexed or i % indexed
else ("~~%i~~" % l))
for i, l in enumerate(lst[1:], 1) )
+ ' ...

')

def ludicpr(nmax=100, prloops=4):

print('The first ludic number is 1.') #yield 1 print('

To generate succeeding ludic numbers create an array of ' 'increasing integers starting from 2') lst = list(range(2, nmax + 1)) print(':%s' % _parray(lst)) print('(Loop)') i = 0 while lst and i <prloops: i += 1 print('* Take the first member of the resultant array as the next Ludic number ' '%i.' % lst[0]) #yield lst[0] print("* Remove every%sindexed item from the array (including the first)." % nth(lst[0])) print('::%s' % _parray(lst, indexed=lst[0])) del lst[::lst[0]] if i == 1: print('* (Unrolling a few loops...)') print("""\