OFFSET

1,2

LINKS

G. C. Greubel, Rows n = 1..50 of the triangle, flattened

FORMULA

EXAMPLE

First few rows of the triangle =

1;

2, 4;

2, 4, 4;

3, 6, 6, 9;

2, 4, 4, 6, 4;

4, 8, 8, 12, 8, 16;

2, 4, 4, 6, 4, 8, 4;

4, 8, 8, 12, 8, 16, 8, 16;

3, 6, 6, 9, 6, 12, 6, 12, 9;

...

T(9,6) = 12 = d(9)*d(6) = 3*4.

MATHEMATICA

A143235[n_, k_]:= DivisorSigma[0, n]*DivisorSigma[0, k];

Table[A143235[n, k], {n, 15}, {k, n}]//Flatten (* G. C. Greubel, Sep 12 2024 *)

PROG

(Magma)

A143235:= func< n, k | NumberOfDivisors(n)*NumberOfDivisors(k) >;

[A143235(n, k): k in [1..n], n in [1..14]]; // G. C. Greubel, Sep 12 2024

(SageMath)

def A143235(n, k): return sigma(n, 0)*sigma(k, 0)

flatten([[A143235(n, k) for k in range(1, n+1)] for n in range(1, 15)]) # G. C. Greubel, Sep 12 2024

CROSSREFS

KEYWORD

AUTHOR

Gary W. Adamson, Aug 01 2008

STATUS

approved