A340769 The third-smallest divisor of n-th square number, n>1.

4, 9, 4, 25, 3, 49, 4, 9, 4, 121, 3, 169, 4, 5, 4, 289, 3, 361, 4, 7, 4, 529, 3, 25, 4, 9, 4, 841, 3, 961, 4, 9, 4, 7, 3, 1369, 4, 9, 4, 1681, 3, 1849, 4, 5, 4, 2209, 3, 49, 4, 9, 4, 2809, 3, 11, 4, 9, 4, 3481, 3, 3721, 4, 7, 4, 13, 3, 4489, 4, 9, 4, 5041, 3

Offset

2,1

Comments

The terms are either primes or squares of primes.

Links

Table of n, a(n) for n=2..72.

Mathematica

a[n_] := Divisors[n^2][[3]]; Array[a, 100, 2] (* Amiram Eldar, Jan 20 2021 *)

Prog

(PARI) a(n) = divisors(n^2)[3]; \\ Michel Marcus, Jan 20 2021

Crossrefs

Cf. A020639, A000290, A000040, A001248, A000430.

Sequence in context: A061369 A361400 A291645 * A088377 A066048 A103164

Adjacent sequences: A340766 A340767 A340768 * A340770 A340771 A340772

Keyword

nonn

Author

Charles Kusniec, Jan 20 2021

Status

approved