A098793 Triangle read by rows, 1<=k<=n: T(n,k) = smallest number having exactly as many divisors as n and k together.

2, 4, 6, 4, 6, 6, 6, 16, 16, 12, 4, 6, 6, 16, 6, 16, 12, 12, 64, 12, 24, 4, 6, 6, 16, 6, 12, 6, 16, 12, 12, 64, 12, 24, 12, 24, 6, 16, 16, 12, 16, 64, 16, 64, 12, 16, 12, 12, 64, 12, 24, 12, 24, 64, 24, 4, 6, 6, 16, 6, 12, 6, 12, 16, 12, 6, 64, 24, 24, 36, 24, 48, 24, 48, 36, 48, 24, 60, 4

Offset

1,1

Links

Table of n, a(n) for n=1..79.

Formula

T(n,k) = A005179(A000005(n)+A000005(k)).

Example

Triangle begins:
  2
  4  6
  4  6  6
  6 16 16 12
  4  6  6 16  6
  ...

Mathematica

A005179 = Cases[Import["https://oeis.org/A005179/b005179.txt", "Table"], {_, _}][[All, 2]];
T[n_, k_] := A005179[[DivisorSigma[0, n] + DivisorSigma[0, k]]];
Table[T[n, k], {n, 1, 12}, {k, 1, n}] // Flatten (* Jean-François Alcover, Sep 15 2021 *)

Prog

(PARI) T(n, k) = my(x=numdiv(n)+numdiv(k), y=1); while(numdiv(y)!= x, y++); y; \\ Michel Marcus, Sep 15 2021

Crossrefs

Cf. A000005, A005179.

Sequence in context: A182043 A337937 A138125 * A083220 A085896 A351491

Adjacent sequences: A098790 A098791 A098792 * A098794 A098795 A098796

Keyword

nonn,tabl

Author

Reinhard Zumkeller, Oct 31 2004

Status

approved