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A144704 a(n) = 4^n*(1-2*n). 3
1, -4, -48, -320, -1792, -9216, -45056, -212992, -983040, -4456448, -19922944, -88080384, -385875968, -1677721600, -7247757312, -31138512896, -133143986176, -566935683072, -2405181685760, -10170482556928 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,2

COMMENTS

Hankel transform of A100320.

LINKS

Table of n, a(n) for n=0..19.

Index entries for linear recurrences with constant coefficients, signature (8,-16).

FORMULA

G.f.: (1-12x)/(1-4x)^2.

From Amiram Eldar, Aug 05 2020: (Start)

Sum_{n>=0} 1/a(n) = 1 - arctanh(1/2)/2.

Sum_{n>=0} (-1)^(n+1)/a(n) = 1 + arctan(1/2)/2. (End)

MATHEMATICA

LinearRecurrence[{8, -16}, {1, -4}, 30] (* Harvey P. Dale, Jun 12 2019 *)

CROSSREFS

Sequence in context: A217153 A129002 A291623 * A091904 A192831 A158681

Adjacent sequences:  A144701 A144702 A144703 * A144705 A144706 A144707

KEYWORD

easy,sign

AUTHOR

Paul Barry, Sep 19 2008

STATUS

approved

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Last modified June 16 14:16 EDT 2021. Contains 345057 sequences. (Running on oeis4.)