OFFSET
1,2
COMMENTS
Ignoring (5,7,11,13) another name for this sequence could be "twin prime twins".
LINKS
Harry J. Smith, Table of n, a(n) for n = 1..1000
EXAMPLE
4 is in the sequence because 101, 103, 107, 109 are primes and 105 = 4*30 - 15.
MATHEMATICA
p4Q[n_]:=Module[{c=30n-15}, And@@PrimeQ[{c-4, c-2, c+2, c+4}]]; Select[ Range[ 6000], p4Q] (* Harvey P. Dale, Dec 04 2011 *)
Select[Range[6000], AllTrue[(30 # - 15) + {-4, -2, 2, 4}, PrimeQ] &] (* Michael De Vlieger, Jul 01 2018 *)
PROG
(PARI) { n=0; for (a=1, 391335, x=30*a - 15; if (isprime(x-4) && isprime(x-2) && isprime(x+2) && isprime(x+4), write("b061668.txt", n++, " ", a)) ) } \\ Harry J. Smith, Jul 26 2009
CROSSREFS
KEYWORD
easy,nonn
AUTHOR
Frank Ellermann, Jun 15 2001
EXTENSIONS
More terms from Larry Reeves (larryr(AT)acm.org), Jun 20 2001
STATUS
approved