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 A102715 #15 Sep 08 2022 08:45:16
%S A102715 1,1,1,1,1,1,1,2,2,1,1,2,2,2,1,1,4,4,4,4,1,1,2,8,8,8,2,1,1,6,12,24,24,
%T A102715 12,6,1,1,4,12,24,24,24,12,4,1,1,6,12,24,36,36,24,12,6,1,1,4,24,32,48,
%U A102715 72,48,32,24,4,1,1,10,40,80,80,120,120,80,80,40,10,1,1,4,20,80,240,240
%N A102715 Triangle read by rows: T(n,k) is phi(binomial(n,k)), where phi is Euler's totient function (0 <= k <= n).
%C A102715 Row n contains n+1 terms. Row sums yield A064450.
%F A102715 T(n, k) = A000010(A007318(n, k)) (0 <= k <= n).
%F A102715 T(2n,n) = A066973(n).
%e A102715 T(6,3)=8 because the positive integers relatively prime to binomial(6,3)=20 and not exceeding 20 are 1,3,7,9,11,13,17 and 19.
%e A102715 Triangle begins:
%e A102715 1;
%e A102715 1, 1;
%e A102715 1, 1, 1;
%e A102715 1, 2, 2, 1;
%e A102715 1, 2, 2, 2, 1;
%e A102715 1, 4, 4, 4, 4, 1;
%p A102715 with(numtheory): T:=(n,k)->phi(binomial(n,k)): for n from 0 to 12 do seq(T(n,k),k=0..n) od; # yields sequence in triangular form
%t A102715 Flatten[Table[EulerPhi[Binomial[n, k]], {n, 0, 12}, {k, 0, n}]] (* _Vincenzo Librandi_, May 01 2019 *)
%o A102715 (Magma) /* As triangle */ [[EulerPhi(Binomial(n,k)): k in [0..n]]: n in [0.. 10]]; // _Vincenzo Librandi_, May 01 2019
%Y A102715 Cf. A000010 (totient), A007318 (binomial).
%Y A102715 Cf. A064450, A066973.
%K A102715 nonn,tabl
%O A102715 0,8
%A A102715 _Emeric Deutsch_, Feb 06 2005