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A127462 a(1)=1; for n>1, a(n) = number of earlier terms a(k), 1<=k<=n-1, such that (k+a(k)) is coprime to n. 2
1, 0, 2, 1, 2, 3, 5, 4, 5, 2, 10, 3, 12, 5, 5, 8, 16, 5, 17, 6, 9, 9, 21, 7, 18, 13, 15, 12, 28, 6, 28, 16, 16, 17, 22, 11, 36, 18, 20, 18, 40, 12, 41, 22, 18, 23, 45, 14, 40, 22, 26, 26, 52, 16, 41, 22, 27, 28, 56, 13, 60, 29, 26, 33, 49, 20, 66, 34, 34, 23, 70, 24, 70, 39, 33, 36, 56 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,3

LINKS

Table of n, a(n) for n=1..77.

EXAMPLE

(a(3)+3) is coprime to 6; (a(4)+4) is coprime to 6; and (a(5)+5) is coprime to 6. These 3 cases are the only cases where (a(k)+k) is coprime to 6, for 1<=k<=5. So a(6)=3.

MATHEMATICA

f[l_List] := Block[{n = Length[l] + 1}, Append[l, Count[Table[GCD[n, k + l[[k]]], {k, n - 1}], 1]]]; Nest[f, {1}, 76] (* Ray Chandler, Jan 22 2007 *)

CROSSREFS

Cf. A127460, A127463.

Sequence in context: A259439 A274491 A076492 * A106436 A075758 A125596

Adjacent sequences:  A127459 A127460 A127461 * A127463 A127464 A127465

KEYWORD

nonn

AUTHOR

Leroy Quet, Jan 15 2007

EXTENSIONS

Extended by Ray Chandler, Jan 22 2007

STATUS

approved

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Last modified June 16 21:55 EDT 2021. Contains 345080 sequences. (Running on oeis4.)