A197421 Primes of the form Sum_{k=1..n} prime(k)*prime(k+1).

44839, 60859, 130411, 204749, 303767, 902971, 1027969, 1471633, 2514257, 3658769, 6908719, 7415743, 21966317, 28168523, 32413109, 37049567, 44034163, 47856331, 373881787, 425445073, 443609813, 564963589, 732111109, 758871401, 857997893, 995046653, 2489902577

Offset: 1

Author

Michel Lagneau, Oct 14 2011

Keywords

• nonn

Comments

The corresponding values of n are 22, 24, 30, 34, 38, 52, 54, 60, 70, 78, 94, 96, ....

Examples

			For n = 22, a(1) = 44839 = 2*3 + 3*5 + 5*7 + ....+ 79*83 where 79 = prime(22) and 83 = prime(23).
		

Links

• Charles R Greathouse IV, Table of n, a(n) for n = 1..2243

Crossrefs

Primes in A074745.

Cf. A013918.

Programs

Maple

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:

Mathematica

Select[Table[Sum[Prime[k] Prime[k + 1], {k, n}], {n, 400}], PrimeQ] (* Alonso del Arte, Oct 14 2011 *)

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

Extensions

Incorrect a(2243) and beyond removed from b-file by Andrew Howroyd, Feb 27 2018