OFFSET
1,1
COMMENTS
Many, but not all, of the terms are the smallest prime in a sequence of 8 consecutive primes with first differences equal to 6, 6, 6, 2, 6, 6, 6. -Harvey P. Dale, May 24 2017
Of the first 400 terms, 311 are the smallest prime in a sequence of 8 consecutive primes with first differences equal to 6, 6, 6, 2, 6, 6, 6. - Harvey P. Dale_, May 25 2017
All terms are congruent to 11 (mod 30). - Zak Seidov, May 24 2017 [Proof: Suppose p == x (mod 30). Then all of x, x+6, x+12, x+18, x+20, x+26, x+2, and x+8 must be relatively prime to 30. This implies x = 11. (We cannot have x=1, for then p+2 would be == 3 (mod 30), we cannot have x=7, for then p+18 would be == 25 (mod 30), and so on.) - N. J. A. Sloane, May 24 2017]
REFERENCES
Zak Seidov, posting to the Sequence Fans Mailing List, May 21, 2017.
Peter Munn, postings to the Sequence Fans Mailing List, May 22 and 24, 2017.
LINKS
Harvey P. Dale, Table of n, a(n) for n = 1..400
EXAMPLE
9646271 is included because 9646277, 9646283, 9646289, 9646291, 9646297, 9646303, and 9646309 are all primes.
MATHEMATICA
Select[Prime[Range[10^7]], AllTrue[#+{6, 12, 18, 20, 26, 32, 38}, PrimeQ]&] (* The program uses the AllTrue function from Mathematica version 10 *)
Select[{41, 251, 311}+#&/@(330*Range[0, 1000000])//Flatten, AllTrue[#+{0, 6, 12, 18, 20, 26, 32, 38}, PrimeQ]&] (* Much faster than the first program above *) (* The program uses the AllTrue function from Mathematica version 10 *) (* Harvey P. Dale, May 24 2017 *)
CROSSREFS
KEYWORD
nonn
AUTHOR
Harvey P. Dale, May 24 2017
STATUS
approved