A097490 Primes which are two greater than A097489 terms.

5, 17, 167, 302946354048717875530381041444257, 17164738545781348456175905084853738838912866540727619406614703260339837793050935010265073947

Offset

1,1

Links

Table of n, a(n) for n=1..5.

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", "))) \The n-th lower twin prime twinl(n) = { local(c, x); c=0; x=1; while(c<n, if(isprime(prime(x)+2), c++); x++; ); return(prime(x-1)) }

Crossrefs

Cf. A097489, A097491.

Cf. A001359, A077800.

Sequence in context: A119769 A182066 A090886 * A355277 A309178 A164740

Adjacent sequences: A097487 A097488 A097489 * A097491 A097492 A097493

Keyword

nonn

Author

Cino Hilliard, Aug 24 2004

Extensions

Edited by Don Reble, Apr 16 2007

Status

approved