OFFSET
2,1
LINKS
Charles R Greathouse IV, Table of n, a(n) for n = 2..1000
EXAMPLE
a(10) = 3063 because 3063 = 3*1021, and 1021 + 3 = 2^10.
MAPLE
with(numtheory):for n from 1 to 30 do:x:=2^n:id:=0:for m from 1 to 10000 while(id=0) do:p:=ithprime(m):y:=x-p:if type(y, prime)=true then z:=y*p: id:=1:printf(`%d, `, z): else fi:od:od:
PROG
(PARI) a(n)=my(N=2^n); forprime(p=2, default(primelimit), if(isprime(N-p), return(p*(N-p)))) \\ Charles R Greathouse IV, Jul 31 2011
CROSSREFS
KEYWORD
nonn
AUTHOR
Michel Lagneau, Jul 18 2011
STATUS
approved