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A115634

Expansion of (1-4*x^2)/(1-x^2).

1, 0, -3, 0, -3, 0, -3, 0, -3, 0, -3, 0, -3, 0, -3, 0, -3, 0, -3, 0, -3, 0, -3, 0, -3, 0, -3, 0, -3, 0, -3, 0, -3, 0, -3, 0, -3, 0, -3, 0, -3, 0, -3, 0, -3, 0, -3, 0, -3, 0, -3, 0, -3, 0, -3, 0, -3, 0, -3, 0

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OFFSET

0,3

COMMENTS

Row sums of number triangle A115633.

LINKS

G. C. Greubel, Table of n, a(n) for n = 0..5000

Index entries for linear recurrences with constant coefficients, signature (0,1).

FORMULA

a(n) = 4*0^n - 3*(1 + (-1)^n)/2.

a(n) = Sum_{k=0..n} A115633(n, k).

From G. C. Greubel, Nov 23 2021: (Start)

a(n) = 1 if n = 0, otherwise a(n) = -A010674(n-1).

E.g.f.: 4 - 3*cosh(x). (End)

MATHEMATICA

Join[{1}, -3*Mod[Range[100] -1, 2]] (* G. C. Greubel, Nov 23 2021 *)

CoefficientList[Series[(1-4x^2)/(1-x^2), {x, 0, 100}], x] (* or *) LinearRecurrence[{0, 1}, {1, 0, -3}, 100] (* or *) PadRight[{1}, 100, {-3, 0}] (* Harvey P. Dale, Dec 06 2024 *)

PROG

(Magma) [4*0^n -3*(1+(-1)^n)/2: n in [0..100]]; // G. C. Greubel, Nov 23 2021

(SageMath) [1]+[-3*((n-1)%2) for n in (1..100)] # G. C. Greubel, Nov 23 2021

CROSSREFS

Cf. A010674, A115633.

Sequence in context: A334040 A273128 A183035 * A010674 A021037 A053387

Adjacent sequences: A115631 A115632 A115633 * A115635 A115636 A115637

KEYWORD

easy,sign

AUTHOR

Paul Barry, Jan 27 2006

STATUS

approved

URL: https://oeis.org/A115634

⇱ A115634 - OEIS