|
Search: id:A105075
|
|
|
| A105075 |
|
a(1) = 1; a(n) = sum_{k=1..n-1} phi(a(k) a(n-k)), where phi(m) is the totient function. |
|
+0
1
|
|
| 1, 1, 2, 3, 6, 10, 16, 38, 80, 160, 328, 752, 1712, 4000, 8736, 16940, 34816, 83904, 178304, 433408, 1031552, 2601600, 5193984, 11318272, 26631680, 62674688, 160582656, 336680960, 715578368, 1829193728, 4724027392, 11004676992
(list; graph; listen)
|
|
|
OFFSET
|
1,3
|
|
|
MAPLE
|
with(numtheory): a:=array(1..100): a[1]:=1: for n from 1 to 49 do a[n+1]:=sum(phi(a[k]*a[n+1-k]), k=1..n) od: for i from 1 to 50 do printf(`%d, `, a[i]) od: (Sellers)
|
|
MATHEMATICA
|
a[1] = 1; a[n_] := Sum[ EulerPhi[ a[k] a[n - k]], {k, n - 1}]; Table[ a[n], {n, 32}] (from Robert G. Wilson v (rgwv(AT)rgwv.com), Apr 09 2005)
|
|
CROSSREFS
|
Sequence in context: A023561 A034419 A066895 this_sequence A140669 A001636 A036588
Adjacent sequences: A105072 A105073 A105074 this_sequence A105076 A105077 A105078
|
|
KEYWORD
|
nonn
|
|
AUTHOR
|
Leroy Quet (qq-quet(AT)mindspring.com), Apr 06 2005
|
|
EXTENSIONS
|
More terms from James A. Sellers (sellersj(AT)math.psu.edu) and Robert G. Wilson v (rgwv(AT)rgwv.com), Apr 09 2005
|
|
|
Search completed in 0.002 seconds
|
