|
Search: id:A137233
|
|
|
| A137233 |
|
Number of n-digit even numbers. |
|
+0
1
|
|
| 5, 45, 450, 4500, 45000, 450000, 4500000, 45000000, 450000000, 4500000000, 45000000000, 450000000000, 4500000000000, 45000000000000, 450000000000000, 4500000000000000, 45000000000000000, 450000000000000000
(list; graph; listen)
|
|
|
OFFSET
|
1,1
|
|
|
FORMULA
|
a(n)=9*10^(n-1)/2 if n > 1. - R. J. Mathar (mathar(AT)strw.leidenuniv.nl), May 23 2008
|
|
EXAMPLE
|
a(2) = 45 because there are 45 2-digit even numbers.
|
|
CROSSREFS
|
Cf. A002275, A090843, A097166, A099914, A099915, A037487, A000422, A057138, A014925, A014923, A016313, A002276, A011577, A019518, A053052.
Sequence in context: A121272 A054318 A093140 this_sequence A001449 A130976 A133305
Adjacent sequences: A137230 A137231 A137232 this_sequence A137234 A137235 A137236
|
|
KEYWORD
|
easy,nonn,base
|
|
AUTHOR
|
Ctibor O. ZIZKA (ctibor.zizka(AT)seznam.cz), Mar 08 2008
|
|
EXTENSIONS
|
Corrected and extended by R. J. Mathar (mathar(AT)strw.leidenuniv.nl), May 23 2008
|
|
|
Search completed in 0.002 seconds
|
