A335327 Numbers k such that iphi(k) divides k, where iphi is an infinitary analog of Euler's phi function (A091732).

1, 2, 6, 12, 24, 72, 120, 240, 480, 1440, 2880, 5760, 8640, 17280, 65280, 86400, 120960, 130560, 259200, 391680, 783360, 1566720, 2350080, 4700160, 23500800, 32901120, 47001600, 70502400, 94003200, 470016000, 1410048000, 2820096000, 4294901760, 5640192000, 8460288000

Offset

1,2

Links

Table of n, a(n) for n=1..35.

Example

6 is a term since iphi(6) = 2 is a divisor of 6.

Mathematica

f[p_, e_] := p^(2^(-1 + Position[Reverse @ IntegerDigits[e, 2], 1])); a[1] = 1; iphi[n_] := Times @@ (Flatten@(f @@@ FactorInteger[n]) - 1);  Select[Range[10^5], Divisible[#, a[#]] &]

Crossrefs

Cf. A007694, A091732, A319481.

Sequence in context: A170935 A277173 A163264 * A163895 A309016 A302652

Adjacent sequences: A335324 A335325 A335326 * A335328 A335329 A335330

Keyword

nonn

Author

Amiram Eldar, Jun 01 2020

Status

approved