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A097490
Primes which are two greater than A097489 terms.
5
5, 17, 167, 302946354048717875530381041444257, 17164738545781348456175905084853738838912866540727619406614703260339837793050935010265073947
OFFSET
1,1
LINKS
EXAMPLE
a(3) = 167 = (Product_{k=1..3} A001359(k)) + 2 = 3 * 5 * 11 + 2 = A097489(3) + 2. - Hartmut F. W. Hoft, Apr 27 2021
MATHEMATICA
step[{list_, q_}] := Module[{p=NextPrime[q]}, {Join[list, If[PrimeQ[p+2], {{p, p+2}}, {}]], p}]
smallerTwin[n_] := First[Transpose[First[NestWhile[step, {{{3, 5}}, 3}, Length[First[step[#]]]<=n&]]]]
a097489[n_] := Rest[FoldList[Times, 1, smallerTwin[n]]]
a097490[n_] := Select[Map[#+2&, a097489[n]], PrimeQ]
a097490[39] (* Hartmut F. W. Hoft, Apr 27 2021 *)
PROG
(PARI) fp(n) = p=1; for(x=1, n, p*=twinl(x); if(isprime(p+2), print1(p+2", ")))
twinl(n) = { local(c, x); c=0; x=1; while(c<n, if(isprime(prime(x)+2), c++); x++; ); return(prime(x-1)) }
CROSSREFS
KEYWORD
nonn
AUTHOR
Cino Hilliard, Aug 24 2004
EXTENSIONS
Edited by Don Reble, Apr 16 2007
STATUS
approved