OFFSET
1,1
COMMENTS
Prime numbers of the form of 2^j*3^k +/- 1, which may be called "Near-3-smooth primes".
Such prime numbers can often be proved prime by OpenPFGW.
LINKS
Lei Zhou, Table of n, a(n) for n = 1..10000
EXAMPLE
MATHEMATICA
f[n_] := Block[{p2, p3 = 3^Range[0, Floor@ Log[3, n] + 1]}, p2 = 2^Floor[Log[2, n/p3] + 1]; Min[ Select[ p2*p3, IntegerQ]]];
a={}; ct=0; tsm=1; While[ct<59, cp=tsm-1; If[(PrimeQ[cp])&&(!MemberQ[a, cp]), a=Append[a, cp]; ct++]; cp=cp+2; If[(PrimeQ[cp])&&(!MemberQ[a, cp]), a=Append[a, cp]; ct++]; tsm=f[tsm]]; Print[a]
PROG
(PARI) list(lim)=my(v=List([2]), N); for(n=0, log(lim\2)\log(3), N=2*3^n; while(N<=lim, if(ispseudoprime(N-1), listput(v, N-1)); if(ispseudoprime(N+1), listput(v, N+1)); N<<=1)); vecsort(Vec(v), , 8) \\ Charles R Greathouse IV, Nov 21 2012
CROSSREFS
KEYWORD
nonn
AUTHOR
Lei Zhou, Nov 21 2012
STATUS
approved