A132068 - OEIS

%I #11 Oct 30 2019 16:51:47

%S 1,1,1,1,1,2,1,1,1,1,1,4,1,1,1,1,1,1,1,2,2,2,1,1,2,1,2,1,1,2,4,2,1,1,

%T 1,1,1,1,1,1,1,1,1,4,2,4,1,1,1,1,1,1,1,1,1,1,1,1,1,2,2,4,2,2,1,1,2,3,

%U 1,3,2,1,1,2,2,2,2,2,2,2,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,4,2,4,2,4,1,1,1

%N Irregular array: row n has A000010(n) terms: the sum of the first m terms of row n is the m-th positive integer which is coprime to n.

%C The first term of each row is 1. The sum of the terms of row n is n-1, for n>=2. After the initial 1, the remaining terms of each row are the same forward or backward.

%e The positive integers which are <= 12 and are coprime to 12 are 1,5,7,11. Row 12 of the array is: 1,4,2,4. So we have: 1=1; 1+4=5; 1+4+2=7; 1+4+2+4=11.

%e The first 12 rows of the array:

%e 1;

%e 1;

%e 1,1;

%e 1,2;

%e 1,1,1,1;

%e 1,4;

%e 1,1,1,1,1,1;

%e 1,2,2,2;

%e 1,1,2,1,2,1;

%e 1,2,4,2;

%e 1,1,1,1,1,1,1,1,1,1;

%e 1,4,2,4

%t f[n_] := Block[{g},g = Select[Range[n], GCD[ #, n] == 1 &]; g - Prepend[Most[g], 0]]; Flatten[Array[f, 25]] (* _Ray Chandler_, Nov 01 2007 *)

%Y Cf. A038566, A000010.

%K nonn,tabf

%O 1,6

%A _Leroy Quet_, Oct 30 2007

%E Extended by _Ray Chandler_, Nov 01 2007