This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.
%I A167192 #25 Jan 13 2025 12:31:47
%S A167192 0,1,0,2,1,0,3,1,1,0,4,3,2,1,0,5,2,1,1,1,0,6,5,4,3,2,1,0,7,3,5,1,3,1,
%T A167192 1,0,8,7,2,5,4,1,2,1,0,9,4,7,3,1,2,3,1,1,0,10,9,8,7,6,5,4,3,2,1,0,11,
%U A167192 5,3,2,7,1,5,1,1,1,1,0,12,11,10,9,8,7,6,5,4,3,2,1,0,13,6,11,5,9,4,1,3,5,2,3
%N A167192 Triangle read by rows: T(n,k) = (n-k)/gcd(n,k), 1 <= k <= n.
%H A167192 Indranil Ghosh, <a href="/A167192/b167192.txt">Rows 1..120 of triangle, flattened</a>
%F A167192 T(n,k) = (n-k)/gcd(n,k), 1 <= k <= n.
%F A167192 T(n,k) = A025581(n,k)/A050873(n,k);
%F A167192 T(n,1) = A001477(n-1);
%F A167192 T(n,2) = A026741(n-2) for n > 1;
%F A167192 T(n,3) = A051176(n-3) for n > 2;
%F A167192 T(n,4) = A060819(n-4) for n > 4;
%F A167192 T(n,n-3) = A144437(n) for n > 3;
%F A167192 T(n,n-2) = A000034(n) for n > 2;
%F A167192 T(n,n-1) = A000012(n);
%F A167192 T(n,n) = A000004(n).
%e A167192 The triangle T(n,k) begins:
%e A167192 n\k 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 ...
%e A167192 1: 0
%e A167192 2: 1 0
%e A167192 3: 2 1 0
%e A167192 4: 3 1 1 0
%e A167192 5: 4 3 2 1 0
%e A167192 6: 5 2 1 1 1 0
%e A167192 7: 6 5 4 3 2 1 0
%e A167192 8: 7 3 5 1 3 1 1 0
%e A167192 9: 8 7 2 5 4 1 2 1 0
%e A167192 10: 9 4 7 3 1 2 3 1 1 0
%e A167192 11: 10 9 8 7 6 5 4 3 2 1 0
%e A167192 12: 11 5 3 2 7 1 5 1 1 1 1 0
%e A167192 13: 12 11 10 9 8 7 6 5 4 3 2 1 0
%e A167192 14: 13 6 11 5 9 4 1 3 5 2 3 1 1 0
%e A167192 15: 14 13 4 11 2 3 8 7 2 1 4 1 2 1 0
%e A167192 - _Wolfdieter Lang_, Feb 20 2013
%t A167192 Flatten[Table[(n-k)/GCD[n,k],{n,20},{k,n}]] (* _Harvey P. Dale_, Nov 27 2015 *)
%o A167192 (PARI) for(n=1,10, for(k=1,n, print1((n-k)/gcd(n,k), ", "))) \\ _G. C. Greubel_, Sep 13 2017
%Y A167192 Cf. A054531, A112543, A164306.
%K A167192 nonn,tabl
%O A167192 1,4
%A A167192 _Reinhard Zumkeller_, Oct 30 2009