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A156067
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a(0)=1. a(n)= -2^(n-1)-3*(-1)^n, n>1.
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1
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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
(list; graph; refs; listen; history; internal format)
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OFFSET
| 0,2
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COMMENTS
| The main diagonal of the array of A153130 and its successive differences.
A154589 is the second upper diagonal of the array.
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LINKS
| Vincenzo Librandi, Table of n, a(n) for n = 0..1000
Index to sequences with linear recurrences with constant coefficients, signature (1,2).
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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).
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MATHEMATICA
| Join[{1}, LinearRecurrence[{1, 2}, {2, -5}, 40]] (* From Harvey P. Dale, Dec 11 2011 *)
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CROSSREFS
| Sequence in context: A146104 A120235 A089618 * A101920 A114494 A118964
Adjacent sequences: A156064 A156065 A156066 * A156068 A156069 A156070
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KEYWORD
| easy,sign
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AUTHOR
| Paul Curtz (bpcrtz(AT)free.fr), Feb 03 2009
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