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A057493 Numbers n such that n | 11^n + 10^n. 2
1, 3, 7, 9, 21, 27, 49, 63, 81, 111, 147, 171, 189, 203, 243, 333, 343, 441, 513, 567, 609, 729, 777, 999, 1029, 1143, 1197, 1323, 1421, 1539, 1701, 1791, 1827, 2187, 2331, 2401, 2943, 2997, 3087, 3249, 3429, 3591, 3969, 4107, 4263, 4617, 5103, 5373 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

COMMENTS

From Robert Israel, Feb 23 2017: (Start)

Contains A003594.

Every term other than 1 is divisible by 3 or 7.

If m and n are in the sequence, then so is m*n. (End)

LINKS

Robert Israel, Table of n, a(n) for n = 1..5305 (first 580 terms from Vincenzo Librandi)

MAPLE

select(t -> (10 &^ t + 11 &^ t mod t = 0), [seq(i, i=1..10000, 2)]); # Robert Israel, Feb 23 2017

MATHEMATICA

Select[ Range[ 10000 ], Mod[ PowerMod[ 11, #, # ] + PowerMod[ 10, #, # ], # ] == 0 & ]

PROG

(PARI) is(n)=Mod(11, n)^n+Mod(10, n)^n==0 \\ Charles R Greathouse IV, Feb 23 2017

CROSSREFS

Cf. A003594.

Sequence in context: A057286 A056745 A057263 * A003594 A014854 A108729

Adjacent sequences:  A057490 A057491 A057492 * A057494 A057495 A057496

KEYWORD

nonn

AUTHOR

Robert G. Wilson v, Sep 20 2000

STATUS

approved

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Last modified February 27 08:51 EST 2020. Contains 332301 sequences. (Running on oeis4.)