OFFSET
1,1
LINKS
Amiram Eldar, Table of n, a(n) for n = 1..10000
FORMULA
Primes INTERSECTION {2^i 3^j 5^k +/-1 for i,j,k >= 0}.
EXAMPLE
a(1) = 2 = 2^0 * 3^0 * 5^0 + 1 = 2^0 * 3^1 * 5^0 - 1.
MATHEMATICA
mx = 2^10; t5 = Select[Sort[Flatten[Table[2^i * 3^j * 5^k, {i, 0, Log[2, mx]}, {j, 0, Log[3, mx]}, {k, 0, Log[5, mx]}]]], # <= mx &]; Union[Select[t5 + 1, PrimeQ], Select[t5 - 1, PrimeQ]] (* T. D. Noe, Nov 25 2012 *)
CROSSREFS
KEYWORD
nonn,easy
AUTHOR
Jonathan Vos Post, Nov 24 2012
EXTENSIONS
Corrected by T. D. Noe, Nov 25 2012
STATUS
approved