OFFSET
1,1
COMMENTS
Primes ending in 7 with (SOD-1)/3 integer where SOD is sum of digits. - Ki Punches, Feb 07 2009
Only from 4927 on, there are more composite numbers than primes in {7+30k}, see A227869. - M. F. Hasler, Nov 02 2013
Terms are non-twin primes A007510, except for 7. - Jonathan Sondow, Oct 27 2017
LINKS
Reinhard Zumkeller, Table of n, a(n) for n = 1..1000
C. K. Caldwell, The Prime Pages
Omar E. Pol, Prime numbers in a sieve with 30 columns
Omar E. Pol, Sobre el patrón de los números primos
FORMULA
a(n) = A158573(n)*30 + 7. - Ray Chandler, Apr 07 2009
a(n) = A211890(4,n-1) for n <= 5. - Reinhard Zumkeller, Jul 13 2012
MATHEMATICA
Select[30*Range[0, 100]+7, PrimeQ] (* Harvey P. Dale, Feb 01 2012 *)
Select[Prime[Range[1000]], MemberQ[{7}, Mod[#, 30]]&] (* Vincenzo Librandi, Aug 14 2012 *)
PROG
(Haskell)
a132231 n = a132231_list !! (n-1)
a132231_list = [x | k <- [0..], let x = 30 * k + 7, a010051' x == 1]
-- Reinhard Zumkeller, Jul 13 2012
(Magma) [p: p in PrimesUpTo(3000) | p mod 30 eq 7 ]; // Vincenzo Librandi, Aug 14 2012
(PARI) forstep(p=7, 1999, 30, isprime(p)&&print1(p", ")) \\ M. F. Hasler, Nov 02 2013
CROSSREFS
KEYWORD
nonn,easy
AUTHOR
Omar E. Pol, Aug 15 2007
EXTENSIONS
Extended by Ray Chandler, Apr 07 2009
STATUS
approved