OFFSET
1,1
COMMENTS
All terms == 1 (mod 6). - Robert Israel, Jan 22 2018
LINKS
Robert Israel, Table of n, a(n) for n = 1..10000
EXAMPLE
a(1)=19 because 191, 193, 197 and 199 are all prime.
MAPLE
select(t -> andmap(isprime, [t, 10*t+1, 10*t+3, 10*t+7, 10*t+9]), [seq(i, i=1..2*10^5, 6)]); # Robert Israel, Jan 22 2018
MATHEMATICA
okQ[n_]:=Module[{n10=10n}, And@@PrimeQ[{n10+1, n10+3, n10+7, n10+9}]]
Select[Prime[Range[20000]], okQ] (* Harvey P. Dale, Dec 13 2010 *)
Select[Prime[Range[11000]], AllTrue[10#+{1, 3, 7, 9}, PrimeQ]&] (* Harvey P. Dale, Feb 23 2022 *)
CROSSREFS
KEYWORD
nonn
AUTHOR
Sudipta Das (juitech(AT)vsnl.net), Feb 21 2002
STATUS
approved