|
Search: id:A058072
|
|
|
| A058072 |
|
Numbers n such that sigma(n) divides sigma(n+1), where sigma(n) is sum of positive divisors of n. |
|
+0
3
|
|
| 1, 5, 14, 125, 206, 957, 1253, 1334, 1364, 1634, 1673, 1919, 2685, 2759, 2974, 3127, 4364, 5191, 7615, 11219, 12035, 14841, 18873, 19358, 20145, 24957, 27089, 33998, 36566, 42818, 43817, 47795, 48559, 49955, 50039, 56564, 56975, 58373, 58463
(list; graph; listen)
|
|
|
OFFSET
|
1,2
|
|
|
COMMENT
|
The ratio is always equal to 1, 2 or 3. A002961 is a subset of this sequence. - Paolo P. Lava (ppl(AT)spl.at), Aug 23 2007
|
|
EXAMPLE
|
5 is included because sigma(5) = 6 divides sigma(6) = 12.
|
|
MAPLE
|
with(numtheory); P:=proc(n) local a, i; for i from 1 by 1 to n do a:=sigma(i+1)/sigma(i); if trunc(a)=a then print(i); fi; od; end: P(100000); - Paolo P. Lava (ppl(AT)spl.at), Aug 23 2007
|
|
CROSSREFS
|
Adjacent sequences: A058069 A058070 A058071 this_sequence A058073 A058074 A058075
Sequence in context: A007838 A024167 A077262 this_sequence A027304 A070135 A067857
|
|
KEYWORD
|
nonn
|
|
AUTHOR
|
Leroy Quet (qq-quet(AT)mindspring.com), Nov 11 2000
|
|
EXTENSIONS
|
More terms from Benoit Cloitre (benoit7848c(AT)orange.fr), Jul 27 2002
|
|
|
Search completed in 0.002 seconds
|
