%I #19 Feb 20 2023 15:10:25
%S 44839,60859,130411,204749,303767,902971,1027969,1471633,2514257,
%T 3658769,6908719,7415743,21966317,28168523,32413109,37049567,44034163,
%U 47856331,373881787,425445073,443609813,564963589,732111109,758871401,857997893,995046653,2489902577
%N Primes of the form Sum_{k=1..n} prime(k)*prime(k+1).
%C The corresponding values of n are 22, 24, 30, 34, 38, 52, 54, 60, 70, 78, 94, 96, ....
%H Charles R Greathouse IV, <a href="/A197421/b197421.txt">Table of n, a(n) for n = 1..2243</a>
%e For n = 22, a(1) = 44839 = 2*3 + 3*5 + 5*7 + ....+ 79*83 where 79 = prime(22) and 83 = prime(23).
%p p:=0:for n from 1 to 600 do:p:=p+ithprime(n)*ithprime(n+1): if type(p,prime)=true then printf(`%d, `,p): else fi:od:
%t Select[Table[Sum[Prime[k] Prime[k + 1], {k, n}], {n, 400}], PrimeQ] (* _Alonso del Arte_, Oct 14 2011 *)
%o (PARI) v=List();t=0;p=2;forprime(q=3,1e4,if(isprime(t+=p*q),listput(v,t));p=q);Vec(v) \\ _Charles R Greathouse IV_, Oct 14 2011
%Y Primes in A074745.
%Y Cf. A013918.
%K nonn
%O 1,1
%A _Michel Lagneau_, Oct 14 2011
%E Incorrect a(2243) and beyond removed from b-file by _Andrew Howroyd_, Feb 27 2018
|