A081628 - OEIS

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A081628

a(n) = 2*(-1)^n - (-5)^n.

1, 3, -23, 123, -623, 3123, -15623, 78123, -390623, 1953123, -9765623, 48828123, -244140623, 1220703123, -6103515623, 30517578123, -152587890623, 762939453123, -3814697265623, 19073486328123, -95367431640623, 476837158203123, -2384185791015623, 11920928955078123

(list; graph; refs; listen; history; text; internal format)

OFFSET

0,2

COMMENTS

Inverse binomial transform of A081629.

LINKS

Vincenzo Librandi, Table of n, a(n) for n = 0..1000

Index entries for linear recurrences with constant coefficients, signature (-6,-5).

FORMULA

G.f.: (1+9*x)/((1+x)*(1+5*x)).

E.g.f.: 2*exp(-x) - exp(-5*x).

a(n) = A033999(n)*(2 - A000351(n)). - Elmo R. Oliveira, Dec 05 2023

MATHEMATICA

CoefficientList[Series[(1 + 9 x) / ((1 + x) (1 + 5 x)), {x, 0, 40}], x] (* Vincenzo Librandi, Aug 09 2013 *)

LinearRecurrence[{-6, -5}, {1, 3}, 30] (* Harvey P. Dale, Jan 08 2021 *)

PROG

(Magma) [2*(-1)^n-(-5)^n: n in [0..25]]; // Vincenzo Librandi, Aug 09 2013

CROSSREFS

Cf. A000351, A033999, A081629.

Sequence in context: A006557 A362158 A226611 * A267656 A122883 A196424

Adjacent sequences: A081625 A081626 A081627 * A081629 A081630 A081631

KEYWORD

easy,sign

AUTHOR

Paul Barry, Mar 26 2003

STATUS

approved

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