A301914 - OEIS

%I #17 May 04 2018 22:41:44

%S 1,5,2,6,16,3,9,6,23,18,43,4,60,19,79,25,68,9,28,78,32,57,158,137,75,

%T 111,7,22,69,86,188,65,85,176,75,64,18,239,191,286,116,140,340,338,

%U 257,226,65,23,51,180,30,207,201,265,131,481,94,367,58,85,79

%N a(n) is the least k for which A301913(n) divides 3^k+2.

%C Combined with A301913 and A301915 can be used to eliminate values of 3^k+2 from prime searches.

%H Robert Israel, <a href="/A301914/b301914.txt">Table of n, a(n) for n = 1..10000</a>

%e A301913(1) = 5 and 5 divides 3^1+2 but not 3^0+2, so a(1)=1.

%e A301913(5) = 19 and 19 does not divide 3^k+2 for 0 <= k < 16, however 19 divides 3^16+2, so a(5)=16.

%p subs(FAIL=NULL,[seq( numtheory:-mlog(-2,3,ithprime(i)), i=3..100)]); # _Robert Israel_, May 04 2018

%Y Cf. A301913, A301915.

%K nonn

%O 1,2

%A _Luke W. Richards_, Mar 28 2018

%E Corrected by _Robert Israel_, May 04 2018