A091181 A091180 indexed by A000040.

4, 6, 8, 11, 12, 19, 29, 31, 34, 37, 42, 46, 47, 63, 68, 75, 80, 93, 95, 100, 105, 106, 115, 133, 136, 138, 141, 145, 151, 157, 159, 167, 169, 175, 187, 197, 210, 211, 217, 221, 222, 232, 233, 247, 257, 263, 274, 275, 279, 306, 308, 327, 335, 337, 339, 355, 365

Offset: 1

Author

Ray Chandler, Dec 27 2003

Keywords

• nonn
• easy

Crossrefs

Cf. A088878, A091179, A091180.

Formula

a(n) = k such that A000040(k) = A091180(n).

a(n) = A000720(A091180(n)). - Michel Marcus, Aug 06 2021

Extensions

Offset changed to 1 by Jinyuan Wang, Aug 06 2021