OFFSET
0,4
EXAMPLE
(a(0)+0) is coprime to 12; (a(3)+3) is coprime to 12; (a(4)+4) is coprime to 12; and (a(7)+7) is coprime to 12. These 4 cases are the only cases where (a(k)+k) is coprime to 12, for 0<=k<=11. So a(12)=4.
MATHEMATICA
f[l_List] := Block[{n = Length[l]}, Append[l, Count[Table[GCD[n, k - 1 + l[[k]]], {k, n}], 1]]]; Nest[f, {1}, 78] (* Ray Chandler, Jan 22 2007 *)
CROSSREFS
KEYWORD
nonn
AUTHOR
Leroy Quet, Jan 15 2007
EXTENSIONS
Extended by Ray Chandler, Jan 22 2007
STATUS
approved