A342630 Numbers k such that A340180(k) is prime.

5, 6, 7, 14, 18, 24, 29, 34, 39, 41, 47, 53, 77, 114, 119, 148, 150, 159, 176, 188, 189, 190, 191, 205, 215, 217, 218, 241, 268, 288, 312, 314, 331, 334, 339, 342, 346, 352, 364, 367, 387, 390, 402, 418, 429, 438, 439, 440, 446, 449, 480, 493, 494, 500, 504, 510, 521, 523, 546, 549, 553, 561, 580

Offset

1,1

Links

Robert Israel, Table of n, a(n) for n = 1..5000

Example

a(4) = 14 is a term because A340180(14) = 23 is prime.

Maple

f:= proc(n) local s, k;
  s:= numtheory:-sigma(n);
  add(`if`(igcd(n, k)=1, s mod k, 0), k=1..n-1);
end proc:
select(t -> isprime(f(t)), [$1..1000]);

Crossrefs

Cf. A340180.

Sequence in context: A371029 A111018 A326132 * A347807 A161925 A078694

Adjacent sequences: A342627 A342628 A342629 * A342631 A342632 A342633

Keyword

nonn

Author

J. M. Bergot and Robert Israel, Mar 17 2021

Status

approved