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Search: id:A126030
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| A126030 |
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Riordan array (1/(1+x^3),x/(1+x^3)). |
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+0
2
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| 1, 0, 1, 0, 0, 1, -1, 0, 0, 1, 0, -2, 0, 0, 1, 0, 0, -3, 0, 0, 1, 1, 0, 0, -4, 0, 0, 1, 0, 3, 0, 0, -5, 0, 0, 1, 0, 0, 6, 0, 0, -6, 0, 0, 1, -1, 0, 0, 10, 0, 0, -7, 0, 0, 1, 0, -4, 0, 0, 15, 0, 0
(list; table; graph; listen)
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OFFSET
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0,12
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COMMENT
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Inverse is A111373. Row sums are A050935(n+2). Diagonal sums are an alternating sign version of A000931(n+3) with g.f. 1/(1-x^2+x^3).
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FORMULA
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Number triangle T(n,k)=C(k+(n-k)/3,(n-k)/3)*(-1)^(n-k)*(2*cos(2*pi*(n-k)/3)+1)/3
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EXAMPLE
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Triangle begins
1,
0, 1,
0, 0, 1,
-1, 0, 0, 1,
0, -2, 0, 0, 1,
0, 0, -3, 0, 0, 1,
1, 0, 0, -4, 0, 0, 1,
0, 3, 0, 0, -5, 0, 0, 1,
0, 0, 6, 0, 0, -6, 0, 0, 1,
-1, 0, 0, 10, 0, 0, -7, 0, 0, 1,
0, -4, 0, 0, 15, 0, 0, -8, 0, 0, 1
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CROSSREFS
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Sequence in context: A103612 A083913 A023670 this_sequence A111373 A116376 A102082
Adjacent sequences: A126027 A126028 A126029 this_sequence A126031 A126032 A126033
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KEYWORD
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easy,sign,tabl
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AUTHOR
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Paul Barry (pbarry(AT)wit.ie), Dec 15 2006
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