Motzkin numbers: Difference between revisions
→{{header|Ruby}}: Add Ruby
(Added C# version, arbitrary precision) |
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41 192,137,918,101,841,817
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</pre>
=={{header|Ruby}}==
<lang ruby>require "prime"
motzkin = Enumerator.new do |y|
m = [1,1]
m.each{|m| y << m }
2.step do |i|
m << (m.last*(2*i+1) + m[-2]*(3*i-3)) / (i+2)
m.unshift # an arr with last 2 elements is sufficient
y << m.last
end
end
</lang>
{{out}}
<pre >
0: 1
1: 1
2: 2 prime
3: 4
4: 9
5: 21
6: 51
7: 127 prime
8: 323
9: 835
10: 2188
11: 5798
12: 15511 prime
13: 41835
14: 113634
15: 310572
16: 853467
17: 2356779
18: 6536382
19: 18199284
20: 50852019
21: 142547559
22: 400763223
23: 1129760415
24: 3192727797
25: 9043402501
26: 25669818476
27: 73007772802
28: 208023278209
29: 593742784829
30: 1697385471211
31: 4859761676391
32: 13933569346707
33: 40002464776083
34: 114988706524270
35: 330931069469828
36: 953467954114363 prime
37: 2750016719520991
38: 7939655757745265
39: 22944749046030949
40: 66368199913921497
41: 192137918101841817
</pre>
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