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A377711
Numbers that have a record number of (1+phi)-divisors (A061389).
1
1, 2, 6, 24, 30, 96, 120, 210, 480, 840, 1920, 2310, 3360, 9240, 13440, 30030, 36960, 120120, 147840, 332640, 480480, 1330560, 1921920, 4324320, 8168160, 17297280, 30750720, 32672640, 73513440, 155195040, 294053760, 522762240, 620780160, 1396755360, 2646483840
OFFSET
1,2
COMMENTS
Indices of records in A061389.
The corresponding record values are 1, 2, 4, 6, 8, 10, 12, 16, 20, 24, 28, 32, 40, 48, 56, ... (see the link for more values).
MATHEMATICA
f[p_, e_] := EulerPhi[e] + 1; d[1] = 1; d[n_] := Times @@ f @@@ FactorInteger[n]; 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
CROSSREFS
Subsequence of A025487.
Sequence in context: A110728 A359450 A190424 * A322484 A377710 A066332
KEYWORD
nonn
AUTHOR
Amiram Eldar, Nov 04 2024
STATUS
approved