A181606 Twin primes ending in 9.

19, 29, 59, 109, 139, 149, 179, 199, 229, 239, 269, 349, 419, 569, 599, 619, 659, 809, 829, 859, 1019, 1049, 1229, 1279, 1289, 1319, 1429, 1489, 1609, 1619, 1669, 1699, 1789, 1879, 1949, 1999, 2029, 2089, 2129, 2239, 2269, 2309, 2339, 2549, 2659, 2689

Offset

1,1

Links

Robert Israel, Table of n, a(n) for n = 1..10000

Omar E. Pol, Determinacion geometrica de los numeros primos y perfectos

Maple

filter:= proc(n)
  if not isprime(n) then return false fi;
  if n mod 3 = 1 then isprime(n-2) else isprime(n+2) fi
end proc:
select(filter, [seq(i, i=9..10^4, 10)]); # Robert Israel, Nov 19 2023

Mathematica

Select[Prime@ Range@ 800, Mod[ #, 10] == 9 && (PrimeQ[ # - 2] || PrimeQ[ # + 2]) &] (* Robert G. Wilson v, Nov 06 2010 *)
Select[Union[Flatten[Select[Partition[Prime[Range[400]], 2, 1], #[[2]]-#[[1]]==2&]]], Mod[#, 10]==9&] (* Harvey P. Dale, May 21 2024 *)

Crossrefs

Cf. A001097, A181603, A181604, A181605.

Union of A060229 and A282324.

Sequence in context: A287313 A136071 A088998 * A139886 A089724 A265804

Adjacent sequences: A181603 A181604 A181605 * A181607 A181608 A181609

Keyword

nonn

Author

Omar E. Pol, Nov 01 2010

Extensions

More terms from Robert G. Wilson v, Nov 06 2010

Status

approved