A356135 Semiprimes k such that k is congruent to 6 modulo k's index in the sequence of semiprimes.

4, 6, 9, 10, 22, 26, 177, 183, 213, 27662, 3066886, 3067021, 3067161, 3067166, 3067186, 3067241, 3067271, 3067421, 3067426, 3067541, 3067561, 3067571, 3067586, 3067661, 3067681, 3067711, 3067741, 3067901, 3067906, 3067991, 3068041, 44690978177, 44690978534, 44690978639, 44690978891

Offset

1,1

Comments

a(42) > 8040423200947.

Links

Lucas A. Brown, Table of n, a(n) for n = 1..41

Lucas A. Brown, semiprimemods.py.

Formula

a(n) = A001358(A106131(n)).

Example

The 1st semiprime is 4, which is congruent to 6 (mod 1), so 4 is in the sequence.
The 2nd semiprime is 6, which is congruent to 6 (mod 2), so 6 is in the sequence.
The 3rd semiprime is 9, which is congruent to 6 (mod 3), so 9 is in the sequence.
The 4th semiprime is 10, which is congruent to 6 (mod 4), so 10 is in the sequence.
The 5th semiprime is 14, which is not congruent to 6 (mod 5), so 14 is not in the sequence.

Crossrefs

Cf. A001358, A106131.

Sequence in context: A118693 A084668 A085842 * A131220 A332618 A295329

Adjacent sequences: A356132 A356133 A356134 * A356136 A356137 A356138

Keyword

nonn,hard

Author

Lucas A. Brown, Oct 14 2022

Status

approved