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.
MATHEMATICA
Select[Range[1, 3001, 4], #==1 || Mod[-PowerMod[#-2, (#-1)/4, #], #]==1&] (* Jean-François Alcover, Nov 18 2018 *)
PROG
(PARI) is(n)=n%4==1 && (2*n-1)*Mod(2, n)^(n>>2)==1 \\ Charles R Greathouse IV, Nov 09 2017
CROSSREFS
KEYWORD
nonn
AUTHOR
Jonas Kaiser, Nov 09 2017
STATUS
approved