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A337573 Numbers k such that Sum_{i=1..k} prime(i)*prime(k+i) is prime. 2

%I #17 Feb 06 2021 22:00:13

%S 2,6,26,34,38,60,102,112,116,122,140,230,236,270,300,330,366,386,418,

%T 426,430,486,488,508,530,534,548,556,568,576,600,674,680,688,696,710,

%U 720,764,772,798,802,804,824,852,870,884,906,982,996,1018,1038,1056,1152,1162,1190,1210,1230,1252,1326

%N Numbers k such that Sum_{i=1..k} prime(i)*prime(k+i) is prime.

%C All terms are even.

%C Numbers k such that A337574(k) is prime.

%H Robert Israel, <a href="/A337573/b337573.txt">Table of n, a(n) for n = 1..8300</a>

%e a(2)=6 is in the sequence because 2*17 + 3*19 + 5*23 + 7*29 + 11*31 + 13*37 = 1231 is prime.

%p P:= <seq(ithprime(i),i=1..6000)>:

%p select(t -> isprime(P[1..t]^%T . P[t+1..2*t]), 2*[$1..1500]);

%t Select[Range[1326], PrimeQ@ Sum[Prime[i] Prime[# + i], {i, #}] &] (* _Michael De Vlieger_, Sep 01 2020 *)

%Y Cf. A000040, A337574.

%K nonn

%O 1,1

%A _J. M. Bergot_ and _Robert Israel_, Sep 01 2020

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Last modified March 29 02:23 EDT 2024. Contains 371264 sequences. (Running on oeis4.)