A052426 Numbers with no two-digit factors (including itself).

1, 2, 3, 4, 5, 6, 7, 8, 9, 101, 103, 107, 109, 113, 127, 131, 137, 139, 149, 151, 157, 163, 167, 173, 179, 181, 191, 193, 197, 199, 202, 206, 211, 214, 218, 223, 226, 227, 229, 233, 239, 241, 251, 254, 257, 262, 263, 269, 271, 274, 277, 278, 281, 283, 293, 298, 302, 303, 307, 309, 311, 313, 314

Offset

1,2

Comments

Numbers of the form k*m where 1 <= k <= 9 and either m=1 or A020639(m) >= 100. - Robert Israel, Mar 11 2018

Links

Robert Israel, Table of n, a(n) for n = 1..10000

Maple

lpf:= n -> min(numtheory:-factorset(n)):
filter:= proc(n) local k;
  for k from 9 to 1 by -1 do
     if n mod k = 0 then return(lpf(n/k) > 100) fi
  od
end proc:
select(filter, [$1..1000]); # Robert Israel, Mar 11 2018

Crossrefs

Cf. A020639.

Sequence in context: A347400 A056544 A082216 * A240237 A056142 A056525

Adjacent sequences: A052423 A052424 A052425 * A052427 A052428 A052429

Keyword

base,nonn

Author

Henry Bottomley, Mar 14 2000

Extensions

Missing terms 277, 281, 283, 293, 307, 311, 313 inserted by Robert Israel, Mar 11 2018

Status

approved