OFFSET
1,4
LINKS
Pierre CAMI, Table of n, a(n) for n = 1..1500
FORMULA
a(n)=1 for n=A003307(i).
EXAMPLE
2^1*3^1-1=5 prime so a(1)=1.
2^1*3^2-1=17 prime so a(2)=1.
2^1*3^3-1=53 prime so a(3)=1.
MATHEMATICA
Flatten[{1, Table[k=0; While[Not[PrimeQ[2^k*3^n-1]], k++]; k, {n, 2, 100}]}] (* Vaclav Kotesovec, Dec 05 2014 *)
PROG
(PFGW & SCRIPT)
SCRIPT
DIM n, 0
DIM k
LABEL loop1
SET n, n+1
SET k, 0
LABEL loop2
SET k, k+1
PRP 2^k*3^n-1
IF ISPRP THEN GOTO loop1
GOTO loop2
CROSSREFS
KEYWORD
nonn
AUTHOR
Pierre CAMI, Dec 03 2014
STATUS
approved