OFFSET
1,1
COMMENTS
These sums, for a given n, can be estimated by the following formula. sum est = x^2/(2*log(x)-1) Where x = prime(n*(n-1)/2+n) For example, n = 10000 x = 982555543 sum est = 23889718028585418 sum act = 23904330028803899 Relative Error = 0.00061127001680771897
FORMULA
EXAMPLE
The consecutive primes 2,3,5,7,11,13 form the triangular grid,
....... 2
..... 3 5
... 7 11 13
These consecutive primes add up to 41, the third entry in the table.
PROG
(PARI) a(n) = sum(x=1, n*(n+1)/2, prime(x))
CROSSREFS
KEYWORD
easy,nonn
AUTHOR
Cino Hilliard, Jan 10 2007
STATUS
approved