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%I #8 Mar 25 2020 11:44:11
%S 1,2,3,3,5,7,4,6,9,11,5,8,12,15,19,6,9,13,16,21,23,7,11,16,20,26,29,
%T 35,8,12,18,22,29,32,39,43,9,14,20,25,33,36,44,49,55,10,15,22,27,35,
%U 38,47,52,59,63,11,17,25,31,40,44,54,60,68,73,83,12,18,26,32,42,46,57,63,71,76,87,91
%N Triangle read by rows: T(m,n) = Sum_{1 <= i <= m, 1 <= j <= n, gcd{i,j}=1} 1, where m >= n >= 1.
%C This is the same triangle as A331781, except the initial row and column of 0's is missing.
%e Triangle begins:
%e 1,
%e 2, 3,
%e 3, 5, 7,
%e 4, 6, 9, 11,
%e 5, 8, 12, 15, 19,
%e 6, 9, 13, 16, 21, 23,
%e 7, 11, 16, 20, 26, 29, 35,
%e 8, 12, 18, 22, 29, 32, 39, 43,
%e 9, 14, 20, 25, 33, 36, 44, 49, 55,
%e 10, 15, 22, 27, 35, 38, 47, 52, 59, 63,
%e 11, 17, 25, 31, 40, 44, 54, 60, 68, 73, 83,
%e 12, 18, 26, 32, 42, 46, 57, 63, 71, 76, 87, 91,
%e ...
%p V0 := proc(m,n) local a,i,j; a:=0;
%p for i from 1 to m do for j from 1 to n do
%p if igcd(i,j)=1 then a:=a+1; fi; od: od: a; end;
%p for m from 1 to 14 do lprint([seq(V0(m,n),n=1..m)]); od:
%Y Cf. A331781. Main diagonal is A018805.
%K nonn,tabl
%O 1,2
%A _N. J. A. Sloane_, Mar 24 2020
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