A113793 Triangle T(n,m) read by rows: T(n,m) = phi(n - m + 1) * phi(m + 1).

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, 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, 12, 4, 10

Offset

1,4

Comments

Row sums are 1, 2, 5, 8, 16, 20, 36, 44, 68, 76, 120, ...

Links

Table of n, a(n) for n=1..66.

Formula

T(n,m) = phi(n - m + 1) * phi(m + 1).

Example

{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, 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, 12, 4, 10}

Mathematica

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

Crossrefs

Cf. A000010.

Sequence in context: A025859 A031281 A203181 * A289499 A215904 A083552

Adjacent sequences: A113790 A113791 A113792 * A113794 A113795 A113796

Keyword

nonn,tabl

Author

Roger L. Bagula and Gary W. Adamson, Aug 25 2008

Status

approved