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A178985 Primes of the form 3^k mod 2^k, in the order in which they are found. 3
3, 19, 11, 227, 1019, 269201, 186023729, 457933343698297657, 2267602862220213494836920572800947269169358383491, 3510117420185552058703020362961660520827436011216742688744177 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

Can it be shown that this is always an increasing sequence?

a(n) is an increasing sequence because a(n) is a subset of the integer sequence b(n) = (fractional part of (3/2)^n without the decimal point)/5^n = A204544(n) / 5^n = prime numbers of A002380. - Michel Lagneau, Jan 25 2012

Corresponding n: 3, 5, 7, 9, 11, 20, 28, 62, 161, 204, 471, 505, 881, 1810, 1812, 2506, 3321, ... - Eric Chen, Jun 13 2018

LINKS

Eric Chen, Table of n, a(n) for n = 1..17

MATHEMATICA

f[n_] := PowerMod[3, n, 2^n]; Select[f@ Range@ 300, PrimeQ]

CROSSREFS

Cf. A002380, A007520.

Sequence in context: A244605 A213602 A145688 * A266704 A185446 A172032

Adjacent sequences:  A178982 A178983 A178984 * A178986 A178987 A178988

KEYWORD

nonn

AUTHOR

Juri-Stepan Gerasimov, Jan 03 2011

STATUS

approved

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Last modified August 4 13:49 EDT 2020. Contains 336201 sequences. (Running on oeis4.)