OFFSET
1,1
LINKS
EXAMPLE
a(2) = 3 = 2 + 1 = 2!! + 1 is the 2nd prime of that form.
a(4) = 47 = 2*4*6 - 1 = 6!! - 1 is the 4th prime of that form.
PROG
(Magma) r:=91; I:=[1, 1]; lst1:=[n le 2 select I[n] else (n-1)*Self(n-2): n in [1..r]]; lst2:=[]; for c in [1..r] do a:=lst1[c]; for s in [-1..1 by 2] do p:=a+s; if IsPrime(p) and not p in lst2 then Append(~lst2, p); end if; end for; end for; lst2;
CROSSREFS
KEYWORD
nonn
AUTHOR
Arkadiusz Wesolowski, Jun 19 2016
STATUS
approved