A357781 Semiprimes k such that k is congruent to 1 modulo k's index in the sequence of semiprimes.
4, 82, 85, 106, 121, 133, 142, 166, 169, 217, 3067001, 3067006, 3067286, 3067411, 3067651, 3067691, 3067721, 3067751, 3067771, 3067781, 3067801, 3068071, 348933121, 348933127, 348933199, 348933223, 348933241, 348933259, 348933271, 348933427, 44690978221, 44690978543, 44690978669
Offset: 1
Examples
The 1st semiprime is 4, which is congruent to 1 (mod 1), so 4 is in the sequence. The 4th semiprime is 10, which is congruent to 2 (mod 4), so 10 is not in the sequence. The 27th semiprime is 82, which is congruent to 1 (mod 27), so 82 is in the sequence.
Links
- Lucas A. Brown, Table of n, a(n) for n = 1..44
- Lucas A. Brown, semiprimemods.py
Comments