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A194085 Strong Achilles numbers: Achilles numbers m such that phi(m) is also an Achilles number, where phi(m) denotes Euler's totient function of m. 1
500, 864, 1944, 2000, 2592, 3456, 5000, 10125, 10368, 12348, 12500, 16875, 19652, 19773, 30375, 31104, 32000, 33275, 37044, 40500, 49392, 50000, 52488, 55296, 61731, 64827, 67500, 69984, 78608, 80000, 81000, 83349, 84375, 93312, 108000 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

LINKS

Ray Chandler, Table of n, a(n) for n = 1..656

Project Euler, Problem 302

PROG

(PARI) isA(n)=!ispower(n) && ispowerful(n)

is(n)=isA(n) && isA(eulerphi(n)) \\ Charles R Greathouse IV, Dec 19 2013

CROSSREFS

Cf. A052486 (Achilles numbers)

Sequence in context: A220024 A251813 A045215 * A216114 A005954 A281779

Adjacent sequences:  A194082 A194083 A194084 * A194086 A194087 A194088

KEYWORD

nonn

AUTHOR

Kausthub Gudipati, Aug 14 2011

EXTENSIONS

Extended by Ray Chandler, Aug 16 2011

STATUS

approved

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Last modified July 22 03:22 EDT 2017. Contains 289648 sequences.