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A067781 Numbers n such that phi(n) and sigma(n) are simultaneously perfect squares. 2
1, 170, 364, 679, 5044, 5130, 5670, 5770, 8721, 8736, 9154, 9639, 9809, 14322, 16376, 22413, 27783, 30256, 32025, 37114, 38760, 51455, 71604, 78570, 82615, 88392, 92004, 100821, 101153, 104168, 115430, 121056, 133569, 139954, 148568 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

COMMENTS

A subsequence of A011257. [From M. F. Hasler, Sep 22 2009]

LINKS

Donovan Johnson, Table of n, a(n) for n = 1..5000

FORMULA

A067781 = A006532 intersect A039770. [From M. F. Hasler, Sep 22 2009]

CROSSREFS

Cf. A006532, A039770.

Sequence in context: A043762 A043771 A158221 * A043344 A045153 A045041

Adjacent sequences:  A067778 A067779 A067780 * A067782 A067783 A067784

KEYWORD

nonn

AUTHOR

Benoit Cloitre, Feb 07 2002

STATUS

approved

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Last modified January 23 03:52 EST 2021. Contains 340384 sequences. (Running on oeis4.)