OFFSET
1,1
LINKS
Harvey P. Dale, Table of n, a(n) for n = 1..2000
FORMULA
EXAMPLE
a(1) = Sum_{i=1..1} prime(i)*(prime(i)+1)/2 = T(2) = 3.
a(2) = Sum_{i=1..11} prime(i)*(prime(i)+1)/2 = T(2)+T(3)+T(5)+T(7)+T(11)+T(13)+T(17)+T(19)+T(23)+T(29)+T(31) = 1759.
a(3) = Sum_{i=1..13} prime(i)*(prime(i)+1)/2 = 3323.
a(4) = Sum_{i=1..53} prime(i)*(prime(i)+1)/2 = T(2) + ... + T(241) = 469303.
a(5) = Sum_{i=1..57} prime(i)*(prime(i)+1)/2 = T(2) + ... + T(269) = 605113.
a(6) = Sum_{i=1..58} prime(i)*(prime(i)+1)/2 = T(2) + ... + T(271) = 641969.
a(7) = Sum_{i=1..68} prime(i)*(prime(i)+1)/2 = T(2) + ... + T(337) = 1110587.
MAPLE
T:=n->n*(n+1)/2: a:=proc(n): if isprime(sum(T(ithprime(j)), j=1..n))=true then sum(T(ithprime(j)), j=1..n) else fi end: seq(a(n), n=1..500); # Emeric Deutsch, Apr 06 2006
MATHEMATICA
Select[Accumulate[Table[(n(n+1))/2, {n, Prime[Range[500]]}]], PrimeQ] (* Harvey P. Dale, Jan 25 2015 *)
CROSSREFS
KEYWORD
easy,nonn
AUTHOR
Jonathan Vos Post, Apr 02 2006
EXTENSIONS
More terms from Emeric Deutsch, Apr 06 2006
STATUS
approved