|
Search: id:A088139
|
|
|
| A088139 |
|
a(n)=2a(n-1)-6a(n-2), a(0)=0, a(1)=1. |
|
+0
5
|
|
| 0, 1, 2, -2, -16, -20, 56, 232, 128, -1136, -3040, 736, 19712, 35008, -48256, -306560, -323584, 1192192, 4325888, 1498624, -22958080, -54907904, 27932672, 385312768, 603029504, -1105817600, -5829812224, -5024718848, 24929435648, 80007184384
(list; graph; listen)
|
|
|
OFFSET
|
0,3
|
|
|
FORMULA
|
G.f.: x/(1-2x+6x^2); e.g.f.: exp(x)sin(sqrt(5)x)/sqrt(5); a(n)=((1+isqrt(5))^n-(1-isqrt(5))^n)/(2isqrt(5)); a(n)=Im{(1+isqrt(5))^n/sqrt(5)}; a(n)=sum{k=0..floor(n/2), C(n, 2k+1)(-5)^k}.
|
|
PROGRAM
|
(Other) sage: [lucas_number1(n, 2, 6) for n in xrange(0, 30)] # [From Zerinvary Lajos (zerinvarylajos(AT)yahoo.com), Apr 23 2009]
|
|
CROSSREFS
|
Cf. A084102, A088136, A088137, A045873.
Sequence in context: A093114 A016740 A133922 this_sequence A152556 A113123 A076615
Adjacent sequences: A088136 A088137 A088138 this_sequence A088140 A088141 A088142
|
|
KEYWORD
|
easy,sign
|
|
AUTHOR
|
Paul Barry (pbarry(AT)wit.ie), Sep 20 2003
|
|
|
Search completed in 0.002 seconds
|
