A159458 Numbers m such that m^2 divides A159068(m), where A159068(m) = Sum_{k=1..m} binomial(m,k) * gcd(m,k).

1, 2, 3, 11, 33, 309, 665, 1461, 2323, 6789

Offset: 1

Author

Leroy Quet, Apr 12 2009

Keywords

• nonn
• more

Comments

m divides A159068(m) for all positive integers m.

Crossrefs

Cf. A159068, A159069.

Programs

PARI

is(m) = sum(k=1, m, binomial(m, k)*gcd(k, m))%m^2 == 0; \\ Jinyuan Wang, Aug 10 2021

Extensions

4 more terms from R. J. Mathar, Apr 16 2009

a(10)=6789 from Ray Chandler, Jun 19 2009