OFFSET
1,1
COMMENTS
Or, primes of the form 6k+1 such that the next prime is again of the form 6k'+1.
LINKS
Reinhard Zumkeller, Table of n, a(n) for n = 1..1000
EXAMPLE
The smallest prime of the form 6k+1 such that the next larger prime differs by a multiple of 3 (and thus a multiple of 6), is a(1)=31, the following prime being 31+6=37.
Note that the next larger prime may also differ by 12 (as is the case for 199,211,619,661,997,1201,1237,1459,1531,1789,3049,...), or by 18 (as it is the case for 523,1069,1381,1759,2161,2503,3889,...), etc.
PROG
(PARI) forprime( p=1, 1e4, (o+0-o=p)%3==0 & o%3==1 & print1( precprime(p-1)", "))
(Haskell)
a185934 n = a185934_list !! (n-1)
a185934_list = map (a000040 . (+ 1)) $
elemIndices 1 $ zipWith (*) a039701_list $ tail a039701_list
-- Reinhard Zumkeller, Nov 16 2012
CROSSREFS
KEYWORD
nonn
AUTHOR
M. F. Hasler, Feb 06 2011
STATUS
approved