A113793 - OEIS

%I #22 Jan 15 2025 08:37:51

%S 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 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 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 Triangle read by rows: T(n,m) = phi(n - m + 1) * phi(m), n >= 1, m >= 1.

%F T(n,m) = A000010(m)*A000010(n-m+1), n >= 1, m >= 1. - _Omar E. Pol_, Jan 14 2025

%e {1},

%e {1, 1},

%e {2, 1, 2},

%e {2, 2, 2, 2},

%e {4, 2, 4, 2, 4},

%e {2, 4, 4, 4, 4, 2},

%e {6, 2, 8, 4, 8, 2, 6},

%e {4, 6, 4, 8, 8, 4, 6, 4},

%e {6, 4, 12, 4, 16, 4, 12, 4, 6},

%e {4, 6, 8, 12, 8, 8, 12, 8, 6, 4},

%e {10, 4, 12, 8, 24, 4, 24, 8, 12, 4, 10}

%t T[n_, m_] = EulerPhi[n - m + 1]*EulerPhi[m + 1]; Table[Table[T[n, m], {m, 0, n}], {n, 0, 10}]; Flatten[%]

%Y Column 1 and leading diagonal give A000010.

%Y Middle diagonal gives A127473.

%Y Row sums give A065093.

%K nonn,tabl

%O 1,4

%A _Roger L. Bagula_ and _Gary W. Adamson_, Aug 25 2008

%E Name corrected and more terms added by _Omar E. Pol_, Jan 14 2025