A117975 - OEIS

%I #12 Aug 03 2014 14:01:23

%S 1,1,0,2,1,1,2,1,1,1,3,2,2,2,2,4,2,3,2,3,2,4,3,3,3,3,3,3,6,3,5,3,5,3,

%T 5,3,6,3,5,3,6,2,5,3,5,6,3,5,3,5,2,5,3,5,3,7,4,6,4,6,3,6,4,6,4,6,8,4,

%U 6,4,6,3,8,4,6,3,7,3,8,5,6,5,6,4,8,5,6,4,7,4,7,9,5,6,5,8,3,8,5,6,5,8,3,8,5,10,5,8,5,8,4

%N Triangle where a(1,1)=1; a(n,m) = number of positive integers which are missing from row (n-1) of the triangle, are <= n and are coprime to m.

%e Row 5 of the triangle is [3,2,2,2,2]. There are 4 positive integers (1,4,5,6) which are coprime to 1, are <= 6 and are not among the terms of row 5. There are 2 positive integers (1,5) which are <= 6, are coprime to 2 and are not among the terms of row 5. ...(Skipping over the m = 3, 4 and 5 cases.) There are 2 positive integer (1,5) which are <= 6, are coprime to 6 and do not occur in row 5.

%e So row 6 is [4,2,3,2,3,2].

%t prev = {1}; Flatten[Join[{prev}, Table[prev = Table[Length[Select[Complement[Range[n], prev], CoprimeQ[#, m] &]], {m, n}], {n, 2, 14}]]] (* _T. D. Noe_, Mar 30 2011 *)

%Y Cf. A117974.

%K nonn,tabl

%O 1,4

%A _Leroy Quet_, Apr 06 2006

%E More terms from _Sean A. Irvine_, Mar 27 2011