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A138189 Sequence built on pattern (1,-even,-even) beginning 1,-2,-2. 1
1, -2, -2, 1, -4, -4, 1, -6, -6, 1, -8, -8, 1, -10, -10, 1, -12, -12, 1, -14, -14, 1, -16, -16, 1, -18, -18, 1, -20, -20, 1, -22, -22, 1, -24, -24, 1, -26, -26, 1, -28, -28, 1, -30, -30, 1, -32, -32, 1, -34, -34, 1, -36, -36, 1, -38, -38, 1, -40, -40 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,2

COMMENTS

Partial sums of A138188.

LINKS

Table of n, a(n) for n=0..59.

Index entries for linear recurrences with constant coefficients, signature (0,0,2,0,0,-1).

FORMULA

G.f.: (1-2x-2x^2-x^3)/(1-2x^3+x^6)

MATHEMATICA

Join[{1}, Riffle[Flatten[{-2#, -2#}&/@Range[25]], 1, 3]] (* Harvey P. Dale, Nov 02 2011 *)

CROSSREFS

Sequence in context: A322082 A334770 A274622 * A110090 A196831 A092848

Adjacent sequences:  A138186 A138187 A138188 * A138190 A138191 A138192

KEYWORD

easy,sign

AUTHOR

Paul Barry, Mar 04 2008

STATUS

approved

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Last modified May 6 14:16 EDT 2021. Contains 343586 sequences. (Running on oeis4.)