A377183 - OEIS

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A377183

Positive numbers k such that L(k)-1 is prime, where L(k) is the k-th Lucas number.

%I #21 Nov 29 2024 21:40:48

%S 2,3,6,24,48,96

%N Positive numbers k such that L(k)-1 is prime, where L(k) is the k-th Lucas number.

%C Terms must be 3-smooth. All other terms have trivial factors. No other terms under 10^7 (a(7) > 10^7).

%e 24 is a term because L(24)-1 = 103681 which is prime. Also 24 = 2^2*3^1.

%Y Indices of primes in A001610.

%Y Cf. A000032, A000204, A001606.

%K nonn,more

%O 1,1

%A _Harsh Aggarwal_, Oct 18 2024