OFFSET
1,1
COMMENTS
For a(n) > 3, the first differences of the sequence are divisible by 6. (Is this a conjecture or a theorem?)
MAPLE
isA001359 := proc(p) isprime(p) and isprime(p+2) ; end proc:
isA000430 := proc(p) if isprime(p) then true; else if issqr(p) then isprime(sqrt(p)) ; else false; end if; end if; end proc:
isA181669 := proc(p) if isprime(p) and (p mod 6)= 5 then if numtheory[bigomega](p-1) =2 and isA000430(p+2) then true; else false; end if; else false; end if ; end proc:
isA172240 := proc(n) isprime(n) and not isA181669(n) ; end proc:
isA172487 := proc(n) isA172240(n) and isA001359(n) ; end proc:
for n from 2 to 2000 do if isA172487(n) then printf("%d, ", n) ; end if; end do:
CROSSREFS
KEYWORD
nonn,easy
AUTHOR
Giovanni Teofilatto, Nov 21 2010
STATUS
approved