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A113793 Triangle T(n,m) read by rows: T(n,m) = phi(n - m + 1) * phi(m + 1). 0
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 (list; table; graph; refs; listen; history; text; internal format)
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

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Last modified December 5 09:03 EST 2020. Contains 338944 sequences. (Running on oeis4.)