OFFSET
1,4
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}] (* Ray Chandler, Nov 10 2006 *)
CROSSREFS
KEYWORD
nonn
AUTHOR
Leroy Quet, Nov 06 2006
EXTENSIONS
Extended by Ray Chandler, Nov 10 2006
STATUS
approved