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A066684 Numbers k such that prime(k) is congruent to sigma(k) (mod k), 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. - Donovan Johnson, Mar 14 2010
LINKS
EXAMPLE
prime(5) = 11 is congruent to sigma(5) = 6 (mod 5), so 5 is in the sequence.
MATHEMATICA
Select[ Range[ 1, 10^5 ], Mod[ DivisorSigma[ 1, # ], # ] == Mod[ Prime[ # ], # ] & ]
CROSSREFS
Sequence in context: A247963 A105288 A242915 * A328784 A128124 A182687
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 March 19 01:57 EDT 2024. Contains 370952 sequences. (Running on oeis4.)