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A293394 Numbers n such that (2*n-1)*(2^((n-1)/4)) == 1 mod n. 7
1, 17, 41, 97, 137, 193, 241, 313, 401, 409, 433, 449, 457, 521, 569, 641, 673, 761, 769, 809, 857, 929, 953, 977, 1009, 1129, 1297, 1321, 1361, 1409, 1489, 1657, 1697, 1873, 1993, 2017, 2081, 2137, 2153, 2161 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

COMMENTS

It appears that many elements of this sequence are prime. The first "pseudoprime" in this sequence is 74665.

LINKS

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

Jonas Kaiser, On the relationship between the Collatz conjecture and Mersenne prime numbers, arXiv:1608.00862 [math.GM], 2016.

PROG

(PARI) is(n)=n%4==1 && (2*n-1)*Mod(2, n)^(n>>2)==1 \\ Charles R Greathouse IV, Nov 09 2017

CROSSREFS

Cf. A001133, A244626, A294717.

Sequence in context: A158014 A139879 A281792 * A070179 A155072 A243451

Adjacent sequences:  A293391 A293392 A293393 * A293395 A293396 A293397

KEYWORD

nonn

AUTHOR

Jonas Kaiser, Nov 09 2017

STATUS

approved

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Last modified January 18 20:19 EST 2018. Contains 297865 sequences.