A125748 a(n) is the smallest positive integer such that Sum_{1<=k<=a(n), gcd(k,n)=1} k is >= n.

1, 3, 2, 3, 3, 5, 4, 5, 5, 7, 5, 7, 5, 9, 8, 7, 6, 11, 6, 9, 10, 9, 7, 11, 8, 11, 8, 11, 8, 13, 8, 11, 10, 11, 11, 13, 9, 13, 11, 13, 9, 17, 9, 15, 13, 13, 10, 17, 11, 17, 13, 17, 10, 17, 13, 15, 13, 15, 11, 19, 11, 15, 16, 15, 14, 23, 12, 19, 14, 19, 12, 19, 12, 17, 16, 17, 15, 23, 13

Offset

1,2

Links

Amiram Eldar, Table of n, a(n) for n = 1..10000

Example

The positive integers which are coprime to 12 are 1,5,7,11,13,... Now 1+5 = 6, which is less than 12; but 1+5+7 is 13, which is >= 12. So a(12) = 7.

Mathematica

f[n_] := Block[{k = 1}, While[Plus @@ Select[Range[k], GCD[ #, n] == 1 &] < n, k++ ]; k]; Table[f[n], {n, 80}] (* Ray Chandler, Dec 11 2006 *)

Crossrefs

Cf. A125749, A117893.

Sequence in context: A230847 A234300 A181672 * A058680 A070544 A087713

Adjacent sequences: A125745 A125746 A125747 * A125749 A125750 A125751

Keyword

nonn

Author

Leroy Quet, Dec 06 2006

Extensions

Extended by Ray Chandler, Dec 11 2006

Status

approved