www.mikescher.com/www/statics/euler/Euler_Problem-077_explanation.md

For an extended explanation please look at problem-076, it's basically the same..

Yet again we remember already calculated values in an grid. The only difference is now that our y-axis is the prime index (We generate a few primes with an Sieve of Eratosthenes).

And once we find a number which count is greater five thousand we abort and print this number.

The only mayor difference to problem-076 is that now not every summand is valid. It is possible that you can use prime[7] but not prime[6]. So we have to look at each possible summand individually. This makes unfortunately the optimization where we remember the sum of all values invalid.