OFFSET
1,1
COMMENTS
LINKS
Robert Israel, Table of n, a(n) for n = 1..1000
EXAMPLE
a(5) = 234 = 2*3*3*13 is a term because A339423(234)=2+2*3+2*3*3=26 divides 234.
MAPLE
R:= NULL: count:= 0:
for n from 4 while count < 100 do
if isprime(n) then next fi;
F:= sort(map(t -> t[1]$t[2], ifactors(n)[2]));
if nops(F)=2 then next fi;
T:= 0; P:= 1;
for j from 1 to nops(F)-1 do
P:= P*F[j];
T:= T+P;
od;
if n mod T = 0 then
R:= R, n; count:= count+1
fi
od:
R;
PROG
(PARI) conv(n) = {my(f=factor(n), v=vector(bigomega(n)), k=1); for (i=1, #f~, for (j=1, f[i, 2], v[k] = f[i, 1]; k++; ); ); v; }
f(n) = {my(v=conv(n)); sum(k=1, #v-1, prod(j=1, k, v[j])); } \\ A339423
isok(k) = (bigomega(k) >= 3) && ((k % f(k)) == 0); \\ Michel Marcus, Dec 04 2020
CROSSREFS
KEYWORD
nonn
AUTHOR
J. M. Bergot and Robert Israel, Dec 03 2020
STATUS
approved