1,1

Conjecture: there are only 8 terms.

Table of n, a(n) for n=1..8.

a(6) = 16 is a term because A023896(16) = 64 is a multiple of A340179(16) = 32.

filter:= proc(n) local S, s, t;

S:= select(t -> igcd(t, n)=1, [$1..n-1]);

s:= nops(S)*n/2;

s mod add(s mod t, t=S) = 0;

end proc:

select(filter, [$3..1000]);

Cf. A023896, A340179.

Sequence in context: A120150 A262892 A109441 * A277319 A176986 A325455

Adjacent sequences: A343880 A343881 A343882 * A343885 A343886 A343887

nonn,more

J. M. Bergot and Robert Israel, May 02 2021

approved