A280968 a(n) = A001097(n) + A001097(n+1).

8, 12, 18, 24, 30, 36, 48, 60, 72, 84, 102, 120, 132, 144, 174, 204, 210, 216, 246, 276, 288, 300, 330, 360, 372, 384, 390, 396, 426, 456, 468, 480, 510, 540, 552, 564, 594, 624, 660, 696, 768, 840, 852, 864, 894, 924, 984, 1044, 1092, 1140

Offset

1,1

Links

Table of n, a(n) for n=1..50.

Formula

a(n) = 2*A163656(n).

Mathematica

Total /@ Partition[#, 2, 1] &@ Select[Prime@ Range@ 105, Total@ Boole@ Map[PrimeQ, # + 2 {-1, 1}] > 0 &] (* Michael De Vlieger, Jan 11 2017 *)

Prog

(PARI) {
t=4;
forstep(n=6, 1000, 6,
        if(isprime(n-1)&&isprime(n+1),
           k=2*n; print1((k+t)/2", ")
           ; print1(k", "); t=k
          )
       )
}

Crossrefs

Cf. A001097. Essentially the same as A096281. A163656.

Sequence in context: A075818 A090738 A085103 * A157940 A308494 A087696

Adjacent sequences: A280965 A280966 A280967 * A280969 A280970 A280971

Keyword

nonn

Author

Dimitris Valianatos, Jan 11 2017

Status

approved