|
Search: id:A049030
|
|
|
| A049030 |
|
Sum of sigma(j) for 1<=j<10^n, where sigma(j) = A048050(j) is the sum of the proper divisors >1 of j (excluding 1 and n). |
|
+0
1
|
|
| 16, 3034, 320243, 32226805, 3224444759, 322465138002, 32246681892518, 3224670122682648, 322467031114802292
(list; graph; listen)
|
|
|
OFFSET
|
1,1
|
|
|
LINKS
|
C. Rivera, Prime Puzzles and Problems Connection
|
|
FORMULA
|
At a(3)=320243, for example, take a(3) from A049000: 820741-500498=320243. Compute 500498 from 999*1000/2=499500, split evenly and reverse to 500499-1=500498. Add a 9 and 0 for each successive term.
|
|
EXAMPLE
|
For n=1, the sum of sigma(j), for j<10 is 0+0+0+2+0+5+0+6+3=16, so a(1)=16.
|
|
CROSSREFS
|
Cf. A001065, A048050, A048995.
Sequence in context: A016876 A123282 A091160 this_sequence A051551 A003773 A087519
Adjacent sequences: A049027 A049028 A049029 this_sequence A049031 A049032 A049033
|
|
KEYWORD
|
base,nonn
|
|
AUTHOR
|
Enoch Haga and Jud McCranie (Enokh(AT)comcast.net and j.mccranie(AT)comcast.net)
|
|
|
Search completed in 0.002 seconds
|
