A280968 - OEIS

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

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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