Problem 44321. Van Eck's Sequence's nth member

Created by Mehmet OZC

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834 Solutions
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Last Solution submitted on Jan 24, 2023

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Huajie Zheng on 23 Oct 2018

interesting

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Solution 1427667

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2 Comments

Simone Sabbatini on 29 Jan 2018

I don't understand why in my Matlab software it works for all the x while here it falis for x>=11

function result = VanEcksSequence(n)
A=0;
for i=1:n
if i==1
A(i+1)=0;
else
[C Chigh]=ismember(A(i),A(1:i-1));
if not(Chigh==0)
A(i+1)=i-Chigh;
else
A(i+1) = 0;
end
end
end
result = A(n);
end

Asif Newaz on 15 Dec 2019

@Simone Sabbatini
i dont think ur algorithm is correct. understand the sequence well..
The first term is zero. Then-
If the last term is *new* to the sequence so far then-- The next term is zero.
Otherwise:
The next term is "how far back" this last term occured previousely.

Solution 1305517

1 Comment

1 Comment

Dyuman Joshi on 8 Sep 2021

Quite an innovative way lol

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Problem 44321. Van Eck's Sequence's nth member

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Problem 44321. Van Eck's Sequence's nth member

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