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A293907 Numbers n for which 10^n mod n = 2^k for some positive integer k. 1
6, 12, 14, 24, 28, 34, 46, 48, 52, 56, 68, 72, 84, 92, 96, 112, 117, 123, 126, 136, 144, 168, 186, 192, 204, 208, 224, 228, 249, 252, 266, 272, 288, 328, 336, 356, 372, 384, 392, 408, 416, 448, 464, 488, 498, 504, 516 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

Odd numbers in this sequence: 117, 123, 249, 747, 4043, 5031, 11573, 12129, 14481, 29489, 34719, 35549, 84123, 124631, 173329, 217391, 266799, 458523, 472173, 490561, 551759, 658499, 675431, 721773, 800397, 1375569, 1917843, 2300079, 3194787, 3394893, 4236747, 5031039, 5043957, 5169333, ....

LINKS

Charles R Greathouse IV, Table of n, a(n) for n = 1..10000

EXAMPLE

For n = 6, 10^6 mod 6 = 4 = 2^2;

For n = 14, 10^14 mod 14 = 2 = 2^1;

For n = 84, 10^84 mod 84 = 64 = 2^6;

For n = 272, 10^272 mod 272 = 256 = 2^8.

PROG

(PARI) is(n)=my(k=lift(Mod(10, n)^n)); k>1 && k>>valuation(k, 2)==1 \\ Charles R Greathouse IV, Oct 19 2017

CROSSREFS

Cf. A056969 (10^n modulo n).

Sequence in context: A079946 A315614 A118586 * A259397 A183029 A113791

Adjacent sequences:  A293904 A293905 A293906 * A293908 A293909 A293910

KEYWORD

nonn

AUTHOR

Björn Ch. Buchli, Oct 19 2017

EXTENSIONS

More terms from Michel Marcus, Oct 19 2017

STATUS

approved

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Last modified March 19 19:45 EDT 2019. Contains 321331 sequences. (Running on oeis4.)