A388145 Numbers k such that 3^k + 2 has at least one divisor of the form 3^m + 2 with 1 <= m < k.

5, 7, 9, 12, 13, 17, 21, 22, 25, 27, 29, 31, 32, 33, 37, 41, 42, 45, 47, 49, 52, 53, 57, 59, 61, 62, 65, 67, 69, 72, 73, 77, 81, 82, 85, 86, 87, 89, 92, 93, 97, 101, 102, 105, 107, 109, 112, 113, 115, 117, 121, 122, 125, 127, 129, 132, 133, 137, 141, 142, 143, 145, 147, 149, 152, 153, 157, 161, 162

Offset

1,1

Comments

Numbers k such that for some j < k, k == j (mod A298827(j)).

Links

Robert Israel, Table of n, a(n) for n = 1..10000

Formula

A375324(n) = 3^a(n) + 2.

Example

a(3) = 9 is a term because 3^9 + 2 = 19685 is divisible by 3^1 + 2 = 5.

Maple

select(k -> ormap(j -> 3 &^ k + 2 mod (3^j+2) = 0, [$1 .. k-1]), [$1..200]);

Crossrefs

Cf. A298827, A375324.

Sequence in context: A374786 A184102 A285915 * A075329 A177031 A336008

Adjacent sequences: A388142 A388143 A388144 * A388146 A388147 A388148

Keyword

nonn

Author

Robert Israel, Sep 15 2025

Status

approved