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A341315 Triangle read by rows: T(n,k) = (n+k)/gcd(n,k), n>=0, 0<=k<=n.

%I A341315 #9 Feb 17 2021 13:32:45
%S A341315 0,1,2,1,3,2,1,4,5,2,1,5,3,7,2,1,6,7,8,9,2,1,7,4,3,5,11,2,1,8,9,10,11,
%T A341315 12,13,2,1,9,5,11,3,13,7,15,2,1,10,11,4,13,14,5,16,17,2,1,11,6,13,7,3,
%U A341315 8,17,9,19,2,1,12,13,14,15,16,17,18,19,20,21,2,1,13,7,5,4,17,3,19,5,7,11,23,2
%N A341315 Triangle read by rows: T(n,k) = (n+k)/gcd(n,k), n>=0, 0<=k<=n.
%C A341315 We define gcd(0,0) = 0.
%C A341315 This is half of the array A341314. See that entry for further information.
%e A341315 Triangle begins:
%e A341315   [0]
%e A341315   [1,  2]
%e A341315   [1,  3,  2]
%e A341315   [1,  4,  5,  2]
%e A341315   [1,  5,  3,  7,  2]
%e A341315   [1,  6,  7,  8,  9,  2]
%e A341315   [1,  7,  4,  3,  5, 11,  2]
%e A341315   [1,  8,  9, 10, 11, 12, 13,  2]
%e A341315   [1,  9,  5, 11,  3, 13,  7, 15,  2]
%e A341315   [1, 10, 11,  4, 13, 14,  5, 16, 17,  2]
%e A341315   [1, 11,  6, 13,  7,  3,  8, 17,  9, 19, 2]
%e A341315   [1, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 2]
%e A341315   ...
%Y A341315 Cf. A341314. A054531 is essentially the same triangle.
%Y A341315 See A341316 for the row sums.
%K A341315 nonn,tabl
%O A341315 0,3
%A A341315 _N. J. A. Sloane_, Feb 17 2021