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A066684 Numbers n such that prime(n) is congruent to sigma(n) (mod n), where prime(n) denotes the n-th prime. 0
1, 2, 4, 5, 181, 324, 1253, 252649, 69789901 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

COMMENTS

a(10) > 10^12. [From Donovan Johnson, Mar 14 2010]

LINKS

Table of n, a(n) for n=1..9.

EXAMPLE

prime(5)=11 is congruent to sigma(5)=6 (mod 5), so 5 is a term of the sequence.

MATHEMATICA

Select[ Range[ 1, 10^5 ], Mod[ DivisorSigma[ 1, # ], # ] == Mod[ Prime[ # ], # ] & ]

CROSSREFS

Sequence in context: A247963 A105288 A242915 * A328784 A128124 A182687

Adjacent sequences:  A066681 A066682 A066683 * A066685 A066686 A066687

KEYWORD

nonn,hard,more

AUTHOR

Joseph L. Pe, Jan 11 2002

EXTENSIONS

a(9) from Donovan Johnson, Mar 14 2010

STATUS

approved

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Last modified September 16 07:19 EDT 2021. Contains 347469 sequences. (Running on oeis4.)