%N Least number a(n) such that there are at least n primes in the range (T(k-1), T(k)] for all k >= a(n), where T(k) is the k-th triangular number.
%C All values and even whether the sequence is well defined are conjectural.
%C a(n) is the conjectured index of the last occurrence of n in A066888.
%C It is conjectured that for every n >= 0, a(n) > n.
%C With R_n the n-th Ramanujan prime (A104272), it is conjectured that for every n >= 0, (1/2) R_n <= a(n) < (20/13) R_n. These bounds have been verified for all n up to 8000. For most n <= 8000, we have a(n) > R_n, with exceptions listed in A190881.
%H T. D. Noe, <a href="/A190661/b190661.txt">Table of n, a(n) for n = 0..8000</a>
%e Because it appears that A066888(7) = 1 is the last 1 of that sequence, a(1) = 7.
%Y Cf. A066888, A000217, A000040, A088634, A104272, A190881.
%A _John W. Nicholson_, May 18 2011
%E Edited by _T. D. Noe_, May 19 2011