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A165553 a(n) = (3/2)*(1+(-3)^(n-1)). 2
1, 3, -3, 15, -39, 123, -363, 1095, -3279, 9843, -29523, 88575, -265719, 797163, -2391483, 7174455, -21523359, 64570083, -193710243, 581130735, -1743392199, 5230176603, -15690529803, 47071589415, -141214768239 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,2

COMMENTS

a(n)/a(n-1) tends to -3.

LINKS

Table of n, a(n) for n=0..24.

FORMULA

a(0)=1, a(1)=3, a(n)=3*a(n-2)-2*a(n-1).

G.f.: (1+5x)/(1+2x-3x^2).

a(n)= Sum_{k=0..n} A112555(n,k)*2^(n-k).

CROSSREFS

Cf. A046717, A084247.

Sequence in context: A089875 A035617 A126319 * A056314 A171379 A078631

Adjacent sequences:  A165550 A165551 A165552 * A165554 A165555 A165556

KEYWORD

easy,sign

AUTHOR

Philippe Deléham, Sep 21 2009

STATUS

approved

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Last modified September 26 20:34 EDT 2021. Contains 347672 sequences. (Running on oeis4.)