OFFSET
1,1
COMMENTS
Numbers k such that A001651(k) is prime.
This sequence is infinite because values of the form floor((3*k-1)/2) include all primes except 3.
LINKS
Iain Fox, Table of n, a(n) for n = 1..10000
EXAMPLE
Floor((3*4 - 1)/2) = 5 is prime, so 4 is a term.
Floor((3*5 - 1)/2) = 7 is prime, so 5 is a term.
Floor((3*6 - 1)/2) = 8 is not prime, so 6 is not a term.
MATHEMATICA
Select[Range[200], PrimeQ@ Floor[(3 # - 1)/2] &] (* or *)
Array[Floor[2 (Prime[# + 1] + 1)/3] &, 60] (* Michael De Vlieger, Dec 09 2017 *)
PROG
(PARI) is(n) = isprime(floor((3*n-1)/2))
(PARI) a(n) = floor((2*prime(n+1) + 2)/3)
(PARI) lista(nn) = forprime(p=3, nn, print1(floor((2*p + 2)/3), ", "))
CROSSREFS
KEYWORD
nonn
AUTHOR
Iain Fox, Dec 03 2017
STATUS
approved