|
Search: id:A165470
|
|
|
| A165470 |
|
a(0)=1, a(1)=5, a(n)=20*a(n-2)-a(n-1). |
|
+0
2
|
|
| 1, 5, 15, 85, 215, 1485, 2815, 26885, 29415, 508285, 80015, 10085685, -8485385, 210199085, -379906785, 4583888485, -12182024185, 103859793885, -347500277585, 2424696155285, -9374701706985, 57868624812685
(list; graph; listen)
|
|
|
OFFSET
|
0,2
|
|
|
COMMENT
|
a(n)/a(n-1) tends to -5.
|
|
FORMULA
|
G.f.: (1+6x)/(1+x-20x^2). a(n)= Sum_{k, 0<=k<=n} A112555(n,k)*4^k.
a(n) = (10*4^n-(-5)^n)/9. [From Klaus Brockhaus (klaus-brockhaus(AT)t-online.de), Sep 25 2009]
|
|
CROSSREFS
|
Sequence in context: A064678 A088935 A030487 this_sequence A165625 A058820 A054363
Adjacent sequences: A165467 A165468 A165469 this_sequence A165471 A165472 A165473
|
|
KEYWORD
|
easy,sign
|
|
AUTHOR
|
Philippe DELEHAM (kolotoko(AT)wanadoo.fr), Sep 20 2009
|
|
|
Search completed in 0.002 seconds
|
