OFFSET
1,1
COMMENTS
Subsequence of A007774.
A111192 is a subsequence.
Subsequence of A195118. - Reinhard Zumkeller, Sep 13 2011
LINKS
Reinhard Zumkeller, Table of n, a(n) for n = 1..250
Eric Weisstein's World of Mathematics, Sexy Primes. [The definition in this webpage is unsatisfactory, because it defines a "sexy prime" as a pair of primes.- N. J. A. Sloane, Mar 07 2021]
FORMULA
EXAMPLE
MATHEMATICA
okQ[n_]:=Module[{fi=Transpose[FactorInteger[n]][[1]]}, Length[fi]==2 && Last[fi]-First[fi]==6]; Select[Range[25000], okQ] (* Harvey P. Dale, Apr 18 2011 *)
PROG
(Haskell)
a143205 n = a143205_list !! (n-1)
a143205_list = filter f [1, 3..] where
f x = length pfs == 2 && last pfs - head pfs == 6 where
pfs = a027748_row x
-- Reinhard Zumkeller, Sep 13 2011
CROSSREFS
KEYWORD
nonn,changed
AUTHOR
Reinhard Zumkeller, Jul 30 2008
STATUS
approved