OFFSET
1,1
EXAMPLE
PROG
(PARI) dpsi(n) = n * sumdivmult(n, d, issquarefree(d)/d);
isnotpsi(n) = for (k=1, n-1, if (dpsi(k) == n, return(0)); ); return (1);
isok(n) = !(n%2) && (!istotient(n) && isnotpsi(n)); \\ Michel Marcus, Mar 22 2019
CROSSREFS
KEYWORD
nonn
AUTHOR
Torlach Rush, Mar 20 2019
EXTENSIONS
More terms from Michel Marcus, Mar 22 2019
STATUS
approved