A273974 - OEIS

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A273974

Number of primes <= n-th Catalan number.

0, 0, 1, 3, 6, 13, 32, 82, 226, 651, 1939, 5946, 18637, 59736, 194898, 645742, 2167325, 7359262, 25237989, 87325031, 304549332, 1069685013, 3781189896, 13443608964, 48049822995, 172568075048, 622514907195, 2254799747130, 8197867118026, 29909486953987, 109477635390870

(list; graph; refs; listen; history; text; internal format)

OFFSET

0,4

LINKS

Amiram Eldar, Table of n, a(n) for n = 0..39 (calculated using Kim Walisch's primecount)

Kim Walisch, Fast C++ prime counting function implementation (primecount).

FORMULA

a(n) = A000720(A000108(n)). - Michel Marcus, Nov 10 2016

MATHEMATICA

Table[PrimePi[CatalanNumber[n]], {n, 0, 27}]

PROG

(Magma) [#PrimesUpTo(Catalan(n)): n in [0..18]];