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A181654
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An eigentriangle of the number triangle A181653.
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2
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1, 1, 1, 2, 1, 1, 3, 2, 1, 1, 6, 4, 2, 1, 1, 9, 6, 3, 2, 1, 1, 18, 12, 6, 4, 2, 1, 1, 27, 18, 9, 6, 3, 2, 1, 1, 54, 36, 18, 12, 6, 4, 2, 1, 1, 81, 54, 27, 18, 9, 6, 3, 2, 1, 1, 162, 108, 54, 36, 18, 12, 6, 4, 2, 1, 1
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table;
graph;
refs;
listen;
history;
text;
internal format)
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OFFSET
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0,4
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COMMENTS
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Generalized (conditional) Riordan array with k-th column generated by x^k*if(mod(k,2)=0,(1+x-x^2)/(1-3x^2),(1+x-x^2+x^3)/(1-3x^2)).
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LINKS
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EXAMPLE
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Triangle begins
1,
1, 1,
2, 1, 1,
3, 2, 1, 1,
6, 4, 2, 1, 1,
9, 6, 3, 2, 1, 1,
18, 12, 6, 4, 2, 1, 1,
27, 18, 9, 6, 3, 2, 1, 1,
54, 36, 18, 12, 6, 4, 2, 1, 1,
81, 54, 27, 18, 9, 6, 3, 2, 1, 1,
162, 108, 54, 36, 18, 12, 6, 4, 2, 1, 1
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CROSSREFS
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KEYWORD
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AUTHOR
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STATUS
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approved
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