A057493 Numbers n such that n | 11^n + 10^n.

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

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