login

Reminder: The OEIS is hiring a new managing editor, and the application deadline is January 26.

Row sums of inverse of number triangle A(n,k) = 1/Euler_phi(n+1) if k <= n <= 2k, 0 otherwise.
1

%I #8 Sep 30 2018 04:01:09

%S 1,1,1,1,2,-1,4,-1,2,0,6,-7,8,-2,2,-1,8,-8,12,-10,4,4,12,-21,12,0,6,

%T -8,16,-18,22,-15,4,4,8,-20,24,-6,6,-18,24,-24,30,-18,4,10,24,-51,26,

%U -10,12,-8,28,-28,22,-24,12,8,30,-60

%N Row sums of inverse of number triangle A(n,k) = 1/Euler_phi(n+1) if k <= n <= 2k, 0 otherwise.

%Y Row sums of A127771.

%K sign

%O 0,5

%A _Paul Barry_, Jan 28 2007