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A122438
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Riordan array (1/(1-2x), x(1+2x)).
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2
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1, 2, 1, 4, 4, 1, 8, 8, 6, 1, 16, 16, 16, 8, 1, 32, 32, 32, 28, 10, 1, 64, 64, 64, 64, 44, 12, 1, 128, 128, 128, 128, 120, 64, 14, 1, 256, 256, 256, 256, 256, 208, 88, 16, 1, 512, 512, 512, 512, 512, 496, 336, 116, 18, 1, 1024, 1024, 1024, 1024, 1024, 1024, 912, 512, 148
(list; table; graph; refs; listen; history; internal format)
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OFFSET
| 0,2
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COMMENTS
| Generalized Whitney triangle. Row sums are A045883(n+1). Diagonal sums are A122439.
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FORMULA
| Number triangle T(n,k)=sum{j=0..n-k, C(k,n-k-j)}*2^(n-k)
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EXAMPLE
| Number triangle begins
1,
2, 1,
4, 4, 1,
8, 8, 6, 1,
16, 16, 16, 8, 1,
32, 32, 32, 28, 10, 1,
64, 64, 64, 64, 44, 12, 1
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MATHEMATICA
| T[n_, k_] := Sum[ Binomial[k, n - k - j]*2^(n - k), {j, 0, n - k}]; Table[ T[n, k], {n, 0, 10}, {k, 0, n}] // Flatten - Robert G. Wilson v Sep 14 2006
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CROSSREFS
| Cf. A004070.
Sequence in context: A118976 A138177 A101559 * A156708 A131250 A140693
Adjacent sequences: A122435 A122436 A122437 * A122439 A122440 A122441
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KEYWORD
| easy,nonn,tabl
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AUTHOR
| Paul Barry (pbarry(AT)wit.ie), Sep 05 2006
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EXTENSIONS
| More terms from Robert G. Wilson v Sep 14 2006
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