A111198 -id:A111198 - cp's OEIS frontend

A111157 Numbers k such that sequence A_k in this database does not contain a prime.

4, 7, 12, 35, 56, 66, 82, 118, 132, 141, 143, 144, 145, 152, 156, 173, 252

Offset: 1

N. J. A. Sloane, following a suggestion of Alonso del Arte, Oct 21 2005

That is, the complete sequence A_k, not just the terms that are shown in the entry, does not contain a prime or the negative of a prime. The only exception to this is for sequences with keyword "dead", when only the visible terms are to be considered.
No other terms below 287. Is 287 a member? This requires proof.
I've checked A000287 up to a(25000) and can report that I found no prime. - Robert G. Wilson v, Jun 23 2014
A search of every term of A000287 of form a(2^k-2) has yielded no primes up to a(2^24-2). It shouldn't have any odd terms outside this subsequence, and assuming that its terms' factors are otherwise random, it has a 2.15*10^-8 probability of containing any prime at all. After A000287, the next difficult sequence is A000373, which should contain infinitely many primes, but has none within its first 10000 terms. - Matthew House, Nov 02 2024

PrimeFan, Esoteric Integer Sequences (Gives a different version.)
PrimeFan, Esoteric Integer Sequences [Cached copy]
Index entries for sequences whose definition involves A_n (or An).

Cf. A111198.

a(16) = 173 inserted by Matthew House, Nov 02 2024

cp's OEIS Frontend

A111157 Numbers k such that sequence A_k in this database does not contain a prime.

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