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A335327
Numbers k such that iphi(k) divides k, where iphi is an infinitary analog of Euler's phi function (A091732).
1
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
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
KEYWORD
nonn
AUTHOR
Amiram Eldar, Jun 01 2020
STATUS
approved