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 A113793 #22 Jan 15 2025 08:37:51
%S A113793 1,1,1,2,1,2,2,2,2,2,4,2,4,2,4,2,4,4,4,4,2,6,2,8,4,8,2,6,4,6,4,8,8,4,
%T A113793 6,4,6,4,12,4,16,4,12,4,6,4,6,8,12,8,8,12,8,6,4,10,4,12,8,24,4,24,8,
%U A113793 12,4,10,4,10,8,12,16,12,12,16,12,8,10,4,12,4,20,8,24,8,36,8,24,8,20,4,12
%N A113793 Triangle read by rows: T(n,m) = phi(n - m + 1) * phi(m), n >= 1, m >= 1.
%F A113793 T(n,m) = A000010(m)*A000010(n-m+1), n >= 1, m >= 1. - _Omar E. Pol_, Jan 14 2025
%e A113793 {1},
%e A113793 {1, 1},
%e A113793 {2, 1, 2},
%e A113793 {2, 2, 2, 2},
%e A113793 {4, 2, 4, 2, 4},
%e A113793 {2, 4, 4, 4, 4, 2},
%e A113793 {6, 2, 8, 4, 8, 2, 6},
%e A113793 {4, 6, 4, 8, 8, 4, 6, 4},
%e A113793 {6, 4, 12, 4, 16, 4, 12, 4, 6},
%e A113793 {4, 6, 8, 12, 8, 8, 12, 8, 6, 4},
%e A113793 {10, 4, 12, 8, 24, 4, 24, 8, 12, 4, 10}
%t A113793 T[n_, m_] = EulerPhi[n - m + 1]*EulerPhi[m + 1]; Table[Table[T[n, m], {m, 0, n}], {n, 0, 10}]; Flatten[%]
%Y A113793 Column 1 and leading diagonal give A000010.
%Y A113793 Middle diagonal gives A127473.
%Y A113793 Row sums give A065093.
%K A113793 nonn,tabl
%O A113793 1,4
%A A113793 _Roger L. Bagula_ and _Gary W. Adamson_, Aug 25 2008
%E A113793 Name corrected and more terms added by _Omar E. Pol_, Jan 14 2025