A377184 Numbers k such that L(k)+1 is prime, where L(k) is the k-th Lucas number.

0, 1, 3, 6, 18

Offset

1,3

Comments

Positive terms must be a power of 3 or twice a power of 3. All other terms have trivial factors. No other terms under 10^7 (a(6) > 10^7).

Links

Table of n, a(n) for n=1..5.

Example

18 is a term because L(18)+1 = 5779 which is prime. Also 18 = 2*3^2.

Crossrefs

Indices of primes in A001612.

Cf. A000032, A000204, A001606.

Sequence in context: A117712 A106158 A274103 * A195995 A248324 A341119

Adjacent sequences: A377181 A377182 A377183 * A377185 A377186 A377187

Keyword

nonn,more

Author

Harsh Aggarwal, Oct 18 2024

Status

approved