A364582 a(n) is the least number with exactly n divisors of the form 3*k+1.

1, 4, 16, 28, 80, 112, 320, 280, 784, 560, 1600, 1120, 10000, 2240, 3920, 2800, 25600, 5600, 1310720, 6160, 15680, 11200, 48400, 12320, 110000, 70000, 39200, 24640, 6553600, 30800, 5368709120, 36400, 78400, 179200, 440000, 61600, 343597383680, 1210000, 490000, 80080

Offset: 1

Author

Ilya Gutkovskiy, Jul 28 2023

Keywords

• nonn

Links

• Bert Dobbelaere, Table of n, a(n) for n = 1..200

Crossrefs

Cf. A001817, A005179, A038547, A364583.

Programs

PARI

a(n) = my(k=1); while (sumdiv(k, d, (d%3)==1) != n, k++); k; \\ Michel Marcus, Jul 29 2023

Extensions

More terms from Bert Dobbelaere, Jul 31 2023