A133440 - OEIS

%I #12 Aug 02 2019 19:58:41

%S 1,1,2,2,5,3,9,6,10,7,19,8,25,13,17,18,38,15,46,21,33,27,62,23,58,36,

%T 56,38,90,26,100,54,69,55,84,43,131,66,90,61,155,48,167,80,97,90,191,

%U 67,178,86,139,105,231,81,181,110,166,130,273,76,287,144,175,156,235,100

%N a(1)=1; a(n) = Sum_{1<=k<=n, gcd(k,n)=1} floor(sqrt(k)).

%e The positive integers that are < 12 and are coprime to 12 are 1,5,7,11. The floors of the square roots of these are 1,2,2,3. So a(12) = 1+2+2+3 = 8.

%t Table[Plus @@ (Floor[Sqrt[Select[Range[n], GCD[ #, n] == 1 &]]]), {n, 1, 70}] (* _Stefan Steinerberger_, Dec 01 2007 *)

%K nonn

%O 1,3

%A _Leroy Quet_, Nov 26 2007

%E More terms from _Stefan Steinerberger_, Dec 01 2007