|
|
A140494
|
|
Numbers that cannot be part of the trajectory of any number under repeated application of the map: n -> n + third-smallest number that does not divide n, unless they are the first term of the trajectory.
|
|
4
|
|
|
1, 2, 3, 4, 6, 12, 18, 24, 28, 30, 36, 37, 40, 42, 46, 48, 49, 52, 54, 55, 60, 64, 66, 72, 78, 80, 84, 88, 90, 96, 97, 100, 102, 106, 108, 112, 114, 115, 120, 124, 126, 132, 133, 138, 144, 150, 156, 157, 160, 162, 166, 168, 172, 174, 175, 180, 184, 186, 192, 198, 200
(list;
graph;
refs;
listen;
history;
text;
internal format)
|
|
|
OFFSET
|
1,2
|
|
LINKS
|
|
|
PROG
|
(PARI) third(n) = {my(nb = 0, k = 1); while (nb != 3, if (n % k, nb++); if (nb != 3, k++); ); k; }
f(n) = n + third(n);
canbe(n) = {for (k=1, n, if (k + third(k) == n, return (1)); ); return (0); }
cannotbe(n) = 1 - canbe(n);
lista(nn) = {for (n=1, nn, if (cannotbe(n), print1(n, ", ")); ); } \\ Michel Marcus, Oct 04 2018
|
|
CROSSREFS
|
|
|
KEYWORD
|
nonn
|
|
AUTHOR
|
|
|
EXTENSIONS
|
|
|
STATUS
|
approved
|
|
|
|