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A123876 Riordan array (1/(1+2x), x(1+x)/(1+2x)^2). 3
1, -2, 1, 4, -5, 1, -8, 18, -8, 1, 16, -56, 41, -11, 1, -32, 160, -170, 73, -14, 1, 64, -432, 620, -377, 114, -17, 1, -128, 1120, -2072, 1666, -704, 164, -20, 1, 256, -2816, 6496, -6608, 3649 (list; table; graph; refs; listen; history; text; internal format)
OFFSET

0,2

COMMENTS

Inverse of A116395. Row sums are A123877. Diagonal sums are (-1)^n*A085810(n). Unsigned version is A114164.

LINKS

Table of n, a(n) for n=0..40.

FORMULA

Number triangle T(n,k)=(-1)^(n-k)*sum{j=0..n, C(k,j-k)*C(n,j)*2^(n-j)}

T(n,k) = T(n-1,k-1) - 4*T(n-1,k) + T(n-2,k-1) - 4*T(n-2,k), T(0,0) = T(1,1) = 1, T(1,0) = -2, T(n,k) = 0 if k<0 or if k>n. - Philippe Deléham, Jan 18 2014

EXAMPLE

Triangle begins

1;

-2, 1;

4, -5, 1;

-8, 18, -8, 1;

16, -56, 41, -11, 1;

-32, 160, -170, 73, -14, 1;

CROSSREFS

Sequence in context: A121574 A117317 A124237 * A114164 A176667 A126182

Adjacent sequences:  A123873 A123874 A123875 * A123877 A123878 A123879

KEYWORD

easy,sign,tabl

AUTHOR

Paul Barry, Oct 16 2006

STATUS

approved

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Last modified October 17 19:18 EDT 2018. Contains 316293 sequences. (Running on oeis4.)