A127616 - OEIS

A127616

a(n) = denominator of the continued fraction which has the positive integers which are <= n and are coprime to n as its terms. The terms are written in order from n-1 for the integer part, to 1 for the final term of the continued fraction.

1, 1, 1, 1, 10, 1, 225, 21, 489, 29, 740785, 43, 83120346, 2144, 111382, 200683, 2789144166880, 6270, 764582487395121, 658073, 4282119239, 88713109, 111056404320064218961, 2040581, 3557587238290412640, 36510389904

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OFFSET

1,5

LINKS

Table of n, a(n) for n=1..26.

EXAMPLE

The positive integers coprime to 8 and <= 8 are 1,3,5,7. So a(8) is the denominator of 7 +1/(5 +1/(3 +1/1)) = 151/21.

MATHEMATICA

f[n_] := Select[Range[n], GCD[ #, n] == 1 &]; g[n_] := Denominator[FromContinuedFraction[Reverse[f[n]]]]; Table[g[n], {n, 27}] (* Ray Chandler, Jan 22 2007 *)

CROSSREFS

Cf. A127614, A127615.

Sequence in context: A223512 A131367 A048176 * A277394 A191549 A285647

Adjacent sequences: A127613 A127614 A127615 * A127617 A127618 A127619

KEYWORD

frac,nonn

AUTHOR

Leroy Quet, Jan 19 2007

EXTENSIONS

Extended by Ray Chandler, Jan 22 2007

STATUS

approved