Riordan numbers: Difference between revisions
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Python example
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The one thousandth: 51077756867821111314...79942013897484633052 (472 digits)
The ten thousandth: 19927418577260688844...71395322020211157137 (4,765 digits)
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=={{header|Python}}==
<syntaxhighlight lang=python>def Riordan(N):
a = [1, 0, 1]
for n in range(3, N):
a.append((n - 1) * (2 * a[n - 1] + 3 * a[n - 2]) // (n + 1))
return a
rios = Riordan(10_000)
for i in range(32):
print(f'{rios[i] : 18,}', end='\n' if (i + 1) % 4 == 0 else '')
print(f'The 1,000th Riordan has {len(str(rios[999]))} digits.')
print(f'The 10,000th Rirdan has {len(str(rios[9999]))} digits.')
</syntaxhighlight>{{out}}
<pre>
1 0 1 1
3 6 15 36
91 232 603 1,585
4,213 11,298 30,537 83,097
227,475 625,992 1,730,787 4,805,595
13,393,689 37,458,330 105,089,229 295,673,994
834,086,421 2,358,641,376 6,684,761,125 18,985,057,351
54,022,715,451 154,000,562,758 439,742,222,071 1,257,643,249,140
The 1,000th Riordan has 472 digits.
The 10,000th Rirdan has 4765 digits.
</pre>
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