everything is four

alles_is_vier.py

import sys

CACHE_LIMIT = 200
POWERS = [
    0,
    1,
    2,
    3,
    6,
    9,
    12,
    15,
    18,
    21,
    24,
    27,
    30,
    33,
    36,
    39,
    42,
    45,
    48,
    51,
    54,
    57,
    60,
    63,
    66,
    69,
    72,
    75,
    78,
    81,
    84,
    87,
    90,
    93,
    96,
    99,
    100
]

NAMES = [
    "",
    "tig",
    "honderd",
    "duizend",
    "miljoen",
    "miljard",
    "biljoen",
    "biljard",
    "triljoen",
    "triljard",
    "quadriljoen",
    "quadriljard",
    "quintiljoen",
    "quintiljard",
    "sextiljoen",
    "sextiljard",
    "septiljoen",
    "septiljard",
    "octiljoen",
    "octiljard",
    "noniljoen",
    "noniljard",
    "deciljoen",
    "deciljard",
    "undeciljoen",
    "undeciljard",
    "duodeciljoen",
    "duodeciljard",
    "tredeciljoen",
    "tredeciljard",
    "quattuordeciljoen",
    "quattuordeciljard",
    "quindeciljoen",
    "quindeciljard",
    "sedeciljoen",
    "sedeciljard",
    "googol"
]

TENS = [
    "",
    "tien",
    "twintig",
    "dertig",
    "veertig",
    "vijftig",
    "zestig",
    "zeventig",
    "tachtig",
    "negentig"
]

NUMBERS = [
    'nul',
    'een',
    'twee',
    'drie',
    'vier',
    'vijf',
    'zes',
    'zeven',
    'acht',
    'negen',
    'tien',
    'elf',
    'twaalf',
    'dertien',
    'veertien', 
    'vijftien',
    'zestien',
    'zeventien',
    'achttien',
    'negentien'
]

def number_to_string( number, start = True, main = True ):
    """
    Convert numbers to text (Dutch)
    """
    string = ""

    for i in range(len(POWERS)-1, 0, -1):
        oom = pow(10,POWERS[i])
        if ( number == 0 and not start ):
            return ""
        if ( number < 20 ):
            return( NUMBERS[number] )
        if ( number < 100 and number >= 20 ):
            r = number % 10
            if ( r == 0 ):
                return( TENS[ number // 10 ] )
            else:
                return( number_to_string( r, False, False ) + "en" + TENS[ number // 10 ])
        if ( number >= oom ):
            n = number // oom
            prefix = ''
            divider = ''
            if main:
                divider = " "
            if (n > 1):
                prefix = number_to_string( n, False, False )
            return( prefix + NAMES[i] + divider + number_to_string( number % oom, False ) )

cache = dict()
def create_chain( number ):
    """
    Starting with the input number, write it out in natural language, then count the number of characters in that, then write that out, etc.

    Stop when a loop is reached.

    Return chain of numbers visited
    """
    visited = set()
    chain = []
    while number not in visited:
        if ( number in cache ):
            chain.extend( cache[number] )
            return ( chain )
        visited.add( number )
        chain.append( number )
        number = len(number_to_string(number))
    return ( chain )

def print_chain( chain ):
    """pretty-print a chain"""
    print ( chain[0], len(chain) )
    for y in chain:
        print( "\t", y, number_to_string( y ) )

if len(sys.argv) > 1:
    print_chain( create_chain( int( sys.argv[1] ) ) )
else:
    x = 0
    best = ( 0, 0, [0] )
    while True:
        chain = create_chain( x )
        if x not in cache and x < CACHE_LIMIT:
            cache[x] = chain
        if len(chain) > len(best):
            best = chain
            print( "\n\n" )
            print_chain( chain )
        x = x + 1
        print( x, number_to_string( x ), "                           ", end = "\r" )