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A153427 Numbers n such that phi(n)=p^2, where p is product of digits of n. 3
1, 12, 125, 451, 4612, 5412, 8313, 22165, 31815, 34125, 43216, 62232, 111398, 115264, 115625, 126225, 142352, 191425, 194313, 235431, 243135, 261532, 265421, 632613, 726313, 852125, 962312, 1142536, 1148316, 1156324, 1162825, 1183491, 1671183, 1672125, 1815912, 1831525, 1914157, 2124535, 2228224, 2321375, 2364132, 2463312, 3356122, 3416541, 3541252, 3716118, 3741812, 4128831, 4218912, 4331236, 4522136, 5148512, 5181293, 5183219, 5463161, 6219612, 6288113, 6411925, 6811922, 7452313, 7518119, 8741341, 9115625, 9324222 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

LINKS

Max Alekseyev, Table of n, a(n) for n = 1..649

EXAMPLE

phi(2228224)=(2*2*2*8*2*2*4)^2, so 2228224 is in the sequence.

MATHEMATICA

Do[If[Apply[Times, IntegerDigits[n]]^2==EulerPhi[n], Print[n]], {n, 1200000}]

Select[Range[94*10^5], EulerPhi[#]==(Times@@IntegerDigits[#])^2&] (* Harvey P. Dale, May 03 2020 *)

CROSSREFS

Cf. A068572, A153428.

Sequence in context: A209041 A155595 A070312 * A178626 A223322 A061114

Adjacent sequences:  A153424 A153425 A153426 * A153428 A153429 A153430

KEYWORD

base,nonn

AUTHOR

Farideh Firoozbakht, Jan 02 2009

EXTENSIONS

a(33)-a(649) from Max Alekseyev, Aug 18 2013, May 31 2018

STATUS

approved

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Last modified May 26 00:32 EDT 2020. Contains 334613 sequences. (Running on oeis4.)