%I #20 Sep 03 2024 08:25:36
%S 0,0,1,3,6,13,32,82,226,651,1939,5946,18637,59736,194898,645742,
%T 2167325,7359262,25237989,87325031,304549332,1069685013,3781189896,
%U 13443608964,48049822995,172568075048,622514907195,2254799747130,8197867118026,29909486953987,109477635390870
%N Number of primes <= n-th Catalan number.
%H Amiram Eldar, <a href="/A273974/b273974.txt">Table of n, a(n) for n = 0..39</a> (calculated using Kim Walisch's primecount)
%H Kim Walisch, <a href="https://github.com/kimwalisch/primecount">Fast C++ prime counting function implementation (primecount)</a>.
%F a(n) = A000720(A000108(n)). - _Michel Marcus_, Nov 10 2016
%t Table[PrimePi[CatalanNumber[n]], {n, 0, 27}]
%o (Magma) [#PrimesUpTo(Catalan(n)): n in [0..18]];
%Y Cf. A000108, A000720, A054782, A277062, A277063.
%K nonn
%O 0,4
%A _Vincenzo Librandi_, Nov 10 2016
%E a(28)-a(30) from _Amiram Eldar_, Sep 03 2024