A342591 Numbers k such that A340740(k) <= k.

1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 24, 25, 26, 28, 30, 32, 33, 34, 36, 40, 42, 46, 48, 54, 60, 78

Offset

1,2

Comments

Numbers k such that Sum_{1<=j<=k/2, j and k coprime} (k-j mod j) <= k.

Conjecture: these are all the terms.

The terms with A340740(k) = k are 19 and 48.

Links

Table of n, a(n) for n=1..38.

Example

a(7) = 7 is a term because A340740(7) = 2 <= 7.

Maple

f:= proc(n) local k;
  add(`if`(igcd(k, n)=1, n mod k, 0), k=1..floor(n/2))
end proc:
select(t -> f(t) <= t, [$1..1000]);

Crossrefs

Cf. A340740

Sequence in context: A080682 A182049 A038770 * A193176 A263314 A267086

Adjacent sequences: A342588 A342589 A342590 * A342592 A342593 A342594

Keyword

nonn,more

Author

J. M. Bergot and Robert Israel, Mar 16 2021

Status

approved