|
Search: id:A124739
|
|
|
| A124739 |
|
a(n) = sum of those positive integers which are coprime to both n and n+1 and which are <= n. |
|
+0
5
|
|
| 1, 1, 1, 4, 1, 6, 9, 13, 8, 20, 13, 24, 29, 25, 32, 64, 37, 54, 61, 61, 55, 110, 73, 91, 111, 108, 114, 168, 91, 120, 225, 170, 153, 199, 144, 216, 305, 221, 175, 320, 211, 252, 397, 261, 249, 506, 337, 342, 423, 351, 403, 624, 433, 410, 483, 431, 493, 812, 421, 480
(list; graph; listen)
|
|
|
OFFSET
|
1,4
|
|
|
LINKS
|
Leroy Quet, Home Page (listed in lieu of email address)
|
|
EXAMPLE
|
The positive integers which are coprime to 8 and which are <= 8 are 1,3,5,7. The integers which are coprime to 9 and which are <= 9 are 1, The integers in both these sequences (1,5,7) are added get a(8) = 13.
|
|
MATHEMATICA
|
f[n_] := Plus @@ Select[Range[n], GCD[n, # ] == GCD[n + 1, # ] == 1 &]; Table[f[n], {n, 60}] (*Chandler*)
|
|
CROSSREFS
|
Cf. A057475, A124738, A124740, A124741.
Sequence in context: A070251 A134234 A154905 this_sequence A122662 A083843 A094264
Adjacent sequences: A124736 A124737 A124738 this_sequence A124740 A124741 A124742
|
|
KEYWORD
|
nonn
|
|
AUTHOR
|
Leroy Quet Nov 06 2006
|
|
EXTENSIONS
|
Extended by Ray Chandler (rayjchandler(AT)sbcglobal.net), Nov 10 2006
|
|
|
Search completed in 0.002 seconds
|
