%I #3 Dec 15 2017 17:36:46
%S 5,5,5,5,5,5,4,3,4,2,3,7,2,6,1,6,1,5,1,4,3,6,7,2,7,5,1,5,5,1,0,6,1,5,
%T 0,6,0,7,0,5,3,6,7,6,6,2,6,7,5,6,0,5,1,1,0,6,0,5,0,0,3,5,6,5,5,5,6,2,
%U 5,5,0,3,1,4,0,4,0,5,0,4,0,4,8,1,3,4,0,6,6,0,4,4,6,3,4,3,3,3,2,4,6,7,4,7,2
%N Number of primes in sequences formed from the t digits of n where the latter terms are given by rule b(i)=sum of t previous terms; primes are counted from initial t digits up to the largest term < n^2.
%e a(21)=7 because there are 7 primes in the sequence
%e 2,1,3,4,7,11,18,29,47,76,123,199,322.
%Y Cf. A007629, A073882.
%K base,easy,nonn
%O 10,1
%A _Jason Earls_, Sep 17 2004