A106126 Numbers k such that k-th semiprime == 1 (mod k).

1, 27, 28, 35, 40, 44, 47, 55, 56, 72, 613400, 613401, 613457, 613482, 613530, 613538, 613544, 613550, 613554, 613556, 613560, 613614, 58155520, 58155521, 58155533, 58155537, 58155540, 58155543, 58155545, 58155571, 6384425460, 6384425506, 6384425524

Offset: 1

Author

Shyam Sunder Gupta, May 07 2005

Keywords

• hard
• nonn

Comments

a(45) > 10^12. - Lucas A. Brown, Oct 17 2020

Examples

			27 is a term because the 27th semiprime (i.e., 82) == 1 (mod 27).
		

Links

• Lucas A. Brown, Table of n, a(n) for n = 1..44
• Lucas A. Brown, semiprimemods.py

Crossrefs

Cf. A001358, A357781.

Extensions

a(23)-a(30) from Donovan Johnson, Oct 29 2008

a(1) and a(31)-a(33) from Lucas A. Brown, Oct 17 2020