A277063 -id:A277063 - cp's OEIS frontend

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

Offset: 0

Vincenzo Librandi, Nov 10 2016

nonn

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).

Cf. A000108, A000720, A054782, A277062, A277063.

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

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

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

a(28)-a(30) from Amiram Eldar, Sep 03 2024

A274771 Number of primes <= n-th Carmichael lambda number.

Original entry on oeis.org

0, 0, 1, 1, 2, 1, 3, 1, 3, 2, 4, 1, 5, 3, 2, 2, 6, 3, 7, 2, 3, 4, 8, 1, 8, 5, 7, 3, 9, 2, 10, 4, 4, 6, 5, 3, 11, 7, 5, 2, 12, 3, 13, 4, 5, 8, 14, 2, 13, 8, 6, 5, 15, 7, 8, 3, 7, 9, 16, 2, 17, 10, 3, 6, 5, 4, 18, 6, 8, 5, 19, 3, 20, 11, 8, 7, 10, 5, 21, 2

Offset: 1

Vincenzo Librandi, Nov 11 2016

nonn

Cf. A002322, A054782, A070804, A273974, A277062, A277063.

[0] cat [#PrimesUpTo(CarmichaelLambda(n)): n in [2..100]];

with(numtheory):
a:= n-> pi(lambda(n)):
seq(a(n), n=1..100);  # Alois P. Heinz, Nov 11 2016

Table[PrimePi[CarmichaelLambda[n]], {n, 100}]

a(n) = A000720(A002322(n)). - Michel Marcus, Nov 11 2016

cp's OEIS Frontend

A273974 Number of primes <= n-th Catalan number.

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