|
| |
|
|
A111150
|
|
a(n) is the number of integers of the form (n+k)/|(n-k)| for k>0.
|
|
2
| |
|
|
2, 4, 6, 6, 6, 10, 6, 8, 10, 10, 6, 14, 6, 10, 14, 10, 6, 16, 6, 14, 14, 10, 6, 18, 10, 10, 14, 14, 6, 22, 6, 12, 14, 10, 14, 22, 6, 10, 14, 18, 6, 22, 6, 14, 22, 10, 6, 22, 10, 16, 14, 14, 6, 22, 14, 18, 14, 10, 6, 30, 6, 10, 22, 14, 14, 22, 6, 14, 14, 22, 6, 28, 6, 10, 22, 14, 14, 22
(list; graph; refs; listen; history; internal format)
|
|
|
|
OFFSET
| 1,1
|
|
|
COMMENTS
| a(n)<=2^(n-1) & a(p)=6 for odd primes. - Robert G. Wilson v.
|
|
|
EXAMPLE
| For n=7 we have integer value for the form when k={5; 6; 8; 9; 14; 21} and (7+k)/|(7-k)| = {6, 13, 15, 8, 3, 2}. Thus a(7) = 6.
|
|
|
MATHEMATICA
| f[n_] := Length[ Select[(n + #)/Abs[n - # ] & /@ Delete[ Range[ Floor[5n/3]], n], IntegerQ[ # ] &]] + 2; Array[f, 78] (* Robert G. Wilson v *)
|
|
|
CROSSREFS
| Sequence in context: A050823 A050825 A174342 * A166983 A078611 A131450
Adjacent sequences: A111147 A111148 A111149 * A111151 A111152 A111153
|
|
|
KEYWORD
| easy,nonn
|
|
|
AUTHOR
| Paolo P. Lava (paoloplava(AT)gmail.com) & Giorgio Balzarotti (greenblue(AT)tiscali.it), Oct 19 2005
|
|
|
EXTENSIONS
| Edited and extended by Robert G. Wilson v (rgwv(at)rgwv.com), Oct 19 2005
|
| |
|
|
