|
Search: id:A048978
|
|
|
| A048978 |
|
Light numbers, those whose mean sum of divisors <= mean running sum of divisors of all previous n. |
|
+0
2
|
|
| 360, 630, 720, 840, 900, 960, 1008, 1080, 1120, 1200, 1260, 1320, 1344, 1400, 1440, 1512, 1540, 1560, 1584, 1620, 1680, 1720, 1760, 1800, 1848, 1872, 1890, 1920, 1980, 2016, 2040, 2100, 2112, 2160, 2184, 2240, 2268, 2280, 2310, 2340, 2352, 2376, 2400
(list; graph; listen)
|
|
|
OFFSET
|
1,1
|
|
|
FORMULA
|
Keep running totals of sum, rs, and number of divisors, rd, for all numbers to n-1. Divide rs by rd. If mean at n <= running mean at n-1, then number is "light, " else "heavy."
|
|
EXAMPLE
|
a(1)=360. At 360 rs/rd of all previous n is 105811/2162=48.94+. At 360, s/d is 1170/24=48.75. 48.75<=48.94 so 360 is "Light."
|
|
CROSSREFS
|
Sequence in context: A063067 A076205 A100417 this_sequence A056502 A056492 A112536
Adjacent sequences: A048975 A048976 A048977 this_sequence A048979 A048980 A048981
|
|
KEYWORD
|
easy,nonn
|
|
AUTHOR
|
Enoch Haga (Enokh(AT)comcast.net)
|
|
|
Search completed in 0.002 seconds
|
