A127615 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 1 for the integer part, to n-1 for the final term of the continued fraction.

1, 1, 2, 3, 30, 5, 972, 115, 2751, 201, 5225670, 401, 701216922, 21376, 1084178, 2304261, 31268240559432, 89634, 9634381345852650, 9512947, 59351535853, 1422376141, 1708512949279640961732, 39380419, 59683863841431305060

Offset

1,3

Links

Table of n, a(n) for n=1..25.

Example

The positive integers coprime to 8 and <= 8 are 1,3,5,7. So a(8) is the denominator of 1 +1/(3 +1/(5 +1/7)) = 151/115.

Mathematica

f[n_] := Select[Range[n], GCD[ #, n] == 1 &]; g[n_] := Denominator[FromContinuedFraction[f[n]]]; Table[g[n], {n, 26}] (* Ray Chandler, Jan 22 2007 *)

Crossrefs

Cf. A127614, A127616.

Sequence in context: A328833 A109886 A277811 * A210417 A278048 A273467

Adjacent sequences: A127612 A127613 A127614 * A127616 A127617 A127618

Keyword

frac,nonn

Author

Leroy Quet, Jan 19 2007

Extensions

Extended by Ray Chandler, Jan 22 2007

Status

approved