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A387093

Composite numbers that contain only prime digits and whose prime factors contain only prime digits.

25, 27, 32, 35, 72, 75, 222, 225, 252, 322, 333, 375, 525, 552, 555, 575, 735, 777, 2352, 2553, 2555, 2775, 3357, 3375, 3552, 3577, 5222, 5352, 5575, 7252, 7322, 23253, 23373, 23532, 23535, 23552, 25275, 25725, 25737, 27232, 27252, 27375, 32352, 32375

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OFFSET

1,1

LINKS

Scott R. Shannon, Table of n, a(n) for n = 1..2298 (all terms < 10^12).

EXAMPLE

25725 is a term as 25725 = 3 * 5^2 * 7^3, and both the number and its prime factors only contain prime digits.

MATHEMATICA

Select[Select[Range[33000], CompositeQ], And[AllTrue[Union@ IntegerDigits[#], PrimeQ], AllTrue[Union@ Flatten@ Map[IntegerDigits, FactorInteger[#][[All, 1]] ], PrimeQ]] &] (* Michael De Vlieger, Aug 16 2025 *)

CROSSREFS

Cf. A061371, A027746, A000040, A019546.

Sequence in context: A350181 A183982 A391998 * A287763 A083806 A239523

Adjacent sequences: A387090 A387091 A387092 * A387094 A387095 A387096

KEYWORD

nonn,base

AUTHOR

Scott R. Shannon and Ursula Ponting, Aug 16 2025

STATUS

approved

URL: https://oeis.org/A387093

⇱ A387093 - OEIS