A250215 Least k such that the n-th weak irregular prime (A250216(n)) divides A241601(k).

11, 23, 32, 13, 15, 44, 7, 27, 29, 19, 63, 24, 22, 43, 129, 130, 62, 75, 133, 84, 211, 127, 164, 100, 84, 9, 20, 156, 88, 87, 280, 19, 71, 125, 163, 100, 200, 382, 126, 159, 240, 215, 196, 130, 94, 292, 141, 400, 86, 270, 222, 175, 389, 52, 45, 22, 592, 522, 20

Offset: 1

Author

Eric Chen, Dec 26 2014

Keywords

• nonn

Comments

A prime p can divide A241601(k) for more than one k; the first few examples are as follows:

p k

67 27, 58

101 63, 68

149 130, 147

157 62, 110

241 211, 239

263 100, 213

307 88, 91, 137

311 87, 193, 292

349 19, 257

353 71, 186, 300

etc.

Examples

			19 is the first weak irregular prime and divides A241601(11) = 50521, so a(1) = 11.
		

Links

• Eric Weisstein's World of Mathematics, Irregular Pair

Crossrefs

Cf. A000928, A035112, A120337, A128197, A250216.

Extensions

More terms from Jinyuan Wang, Feb 18 2022