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A156067
a(0)=1. a(n)= -2^(n-1)-3*(-1)^n, n>1.
2
1, 2, -5, -1, -11, -13, -35, -61, -131, -253, -515, -1021, -2051, -4093, -8195, -16381, -32771, -65533, -131075, -262141, -524291, -1048573, -2097155, -4194301, -8388611, -16777213, -33554435, -67108861, -134217731, -268435453, -536870915, -1073741821, -2147483651
OFFSET
0,2
COMMENTS
The main diagonal of the array of A153130 and its successive differences.
A154589 is the second upper diagonal of the array.
FORMULA
a(n)= +a(n-1) +2*a(n-2), n>2.
G.f.: x*(-2+7*x) / ( (1+x)*(2*x-1) ).
a(n) == A153130(n) (mod 9).
a(n+1)-2*a(n) = (-1)^n*9, n>0.
a(n) = A154589(n)-3*(-1)^n.
a(n)+a(n+3) = -A005010(n-1) = -9*A131577(n).
a(2*n)+a(2*n+1) = -3*2^(2n-1) = -A002023(n-2).
MATHEMATICA
Join[{1}, LinearRecurrence[{1, 2}, {2, -5}, 40]] (* Harvey P. Dale, Dec 11 2011 *)
CROSSREFS
Sequence in context: A089618 A207629 A207614 * A352577 A263487 A101920
KEYWORD
easy,sign
AUTHOR
Paul Curtz, Feb 03 2009
STATUS
approved