A363333 Numbers with a record number of divisors that are both coreful and bi-unitary.

1, 8, 32, 128, 216, 864, 3456, 7776, 13824, 31104, 108000, 279936, 432000, 972000, 1728000, 3888000, 15552000, 34992000, 62208000, 97200000, 139968000, 248832000, 333396000, 559872000, 592704000, 874800000, 1333584000, 5334336000, 12002256000, 21337344000, 33339600000

Offset: 1

Author

Amiram Eldar, May 28 2023

Keywords

• nonn

Comments

Indices of records in A363332.

The corresponding record values are 1, 3, 5, 7, 9, 15, 21, 25, 27, 35, 45, 49, 63, 75, 81, ... (see the link for more values).

Links

• Amiram Eldar, Table of n, a(n) for n = 1..261
• Amiram Eldar, Table of n, a(n), A363332(a(n)) for n = 1..261

Crossrefs

Cf. A363332.

Subsequence of A025487.

Similar sequences: A005934, A293185.

Programs

Mathematica

f[p_, e_] := If[OddQ[e], e, e - 1]; d[1] = 1; d[n_] := Times @@ (f @@@ FactorInteger[n]); Array[a, 120]
v = Cases[Import["https://oeis.org/A025487/b025487.txt", "Table"], {, }][[;; , 2]];
seq = {}; dm = 0; Do[If[(dk = d[v[[k]]]) > dm, dm = dk; AppendTo[seq, v[[k]]]], {k, 1, Length[v]}]; seq