|
Search: id:A113594
|
|
|
| A113594 |
|
a(1) = a(2) = 1; a(n+1) = GCD(sum_{1<=k<=n/2} a(k), sum_{n/2<j<=n} a(j)). |
|
+0
1
|
|
| 1, 1, 1, 1, 2, 2, 1, 3, 4, 4, 2, 2, 8, 8, 1, 1, 6, 12, 4, 16, 20, 20, 2, 2, 4, 8, 8, 16, 40, 40, 1, 1, 2, 2, 6, 12, 12, 12, 32, 64, 16, 80, 20, 100, 120, 120, 2, 2, 4, 4, 4, 8, 8, 8, 16, 16, 16, 32, 40, 200, 240, 240, 1, 1, 2, 2, 2, 4, 6, 6, 12, 12, 24, 24, 12, 12, 72, 144, 32, 64, 192, 384
(list; graph; listen)
|
|
|
OFFSET
|
1,5
|
|
|
COMMENT
|
a(2n-1) divides a(2n), for every positive integer n.
|
|
LINKS
|
Leroy Quet, Home Page (listed in lieu of email address)
|
|
EXAMPLE
|
a(12) = GCD(a(1)+a(2)+a(3)+a(4)+a(5), a(6)+a(7)+a(8)+a(9)+a(10)+a(11)) =
GCD(1+1+1+1+2, 2+1+3+4+4+2) = GCD(6,16) = 2.
|
|
MATHEMATICA
|
a[1] = a[2] = 1; a[n_] := a[n] = GCD[ Sum[a[k], {k, Floor[(n - 1)/2]}], Sum[a[j], {j, Ceiling[n/2], n - 1}]]; Array[a, 82] (* Robert G. Wilson v *)
|
|
CROSSREFS
|
Sequence in context: A089692 A066201 A123956 this_sequence A102563 A121496 A091971
Adjacent sequences: A113591 A113592 A113593 this_sequence A113595 A113596 A113597
|
|
KEYWORD
|
nonn
|
|
AUTHOR
|
Leroy Quet Jan 26 2006
|
|
EXTENSIONS
|
More terms from Robert G. Wilson v (rgwv(at)rgwv.com), Feb 01 2006
|
|
|
Search completed in 0.002 seconds
|
