OFFSET
1,1
COMMENTS
All numbers in this sequence end in 5 because n-4 , n-2 is a twin prime pair and so also is n+2 and n+4.
For all n, a(n) - 4 is in A230668(n). Somewhat surprisingly, all terms of A230668 known so far are of that form. - M. F. Hasler, Dec 08 2016
EXAMPLE
280743771536011785 is a pseudoprime (base 2) and 280743771536011781, 280743771536011783, 280743771536011787 and 280743771536011789 are primes.
CROSSREFS
KEYWORD
nonn,more,hard
AUTHOR
Shyam Sunder Gupta, Oct 27 2013
STATUS
approved