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A087671 Number of subsets S of {0,1,2,...,n-1} which are idempotent under squaring modulo n, where S*S mod n = {x*y mod n|x,y in S}. 0
2, 4, 6, 8, 8, 27, 10, 26, 18, 43, 10, 146, 14, 59, 107, 114, 12, 184, 14, 406, 142, 59 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

LINKS

Table of n, a(n) for n=1..22.

EXAMPLE

{4} is one of the a(6)=27 idempotent (mod 6) subsets of {0,1,2,3,4,5}, since {4}*{4}={16 mod 6}={4}.

CROSSREFS

Sequence in context: A219028 A333557 A062355 * A088308 A167832 A134488

Adjacent sequences:  A087668 A087669 A087670 * A087672 A087673 A087674

KEYWORD

nonn,more

AUTHOR

John W. Layman, Sep 26 2003

STATUS

approved

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Last modified February 28 08:40 EST 2021. Contains 341695 sequences. (Running on oeis4.)