|
|
A046466
|
|
Numbers k such that the concatenation of numbers from 1 to k is the product of 7 primes (not necessarily distinct).
|
|
1
|
|
|
28, 30, 42, 44, 46, 69, 72, 82, 84, 86, 93, 109, 116
(list;
graph;
refs;
listen;
history;
text;
internal format)
|
|
|
OFFSET
|
1,1
|
|
LINKS
|
|
|
MATHEMATICA
|
Select[Range[100], PrimeOmega@FromDigits@Flatten@IntegerDigits@Range@# == 7 &] (* Robert Price, Oct 11 2019 *)
|
|
CROSSREFS
|
|
|
KEYWORD
|
nonn,base,hard,more
|
|
AUTHOR
|
|
|
EXTENSIONS
|
|
|
STATUS
|
approved
|
|
|
|