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A159764
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Riordan array (1/(1+4x+x^2), x/(1+4x+x^2)).
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3
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1, -4, 1, 15, -8, 1, -56, 46, -12, 1, 209, -232, 93, -16, 1, -780, 1091, -592, 156, -20, 1, 2911, -4912, 3366, -1200, 235, -24, 1, -10864, 21468, -17784, 8010, -2120, 330, -28, 1, 40545, -91824, 89238, -48624, 16255, -3416, 441, -32, 1, -151316, 386373
(list; table; graph; refs; listen; history; internal format)
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OFFSET
| 0,2
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COMMENTS
| Row sums are (-1)^n*F(2n+2). Diagonal sums are (-1)^n*4^n. Inverse is A052179.
The positive matrix is (1/(1-4x+x^2),x/(1-4x+x^2)) with general term T(n,k)=if(k<=n, Gegenbauer_C(n-k,k+1,2),0).
For another version, see A124029.
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FORMULA
| Number triangle T(n,k)=if(k<=n, Gegenbauer_C(n-k,k+1,-2),0).
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EXAMPLE
| Triangle begins
1,
-4, 1,
15, -8, 1,
-56, 46, -12, 1,
209, -232, 93, -16, 1,
-780, 1091, -592, 156, -20, 1,
2911, -4912, 3366, -1200, 235, -24, 1
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CROSSREFS
| Sequence in context: A156290 A080419 A095307 * A124029 A056920 A123382
Adjacent sequences: A159761 A159762 A159763 * A159765 A159766 A159767
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KEYWORD
| easy,sign,tabl
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AUTHOR
| Paul Barry (pbarry(AT)wit.ie), Apr 21 2009
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