OFFSET
1,1
COMMENTS
These could be called crooked numbers. Integers all of whose numerals are written (san serif) with at least one right or acute angle. The subsequence of crooked primes begins: 5, 7, 47, 457, 547, 557, 577, 757.
Exponential density 0.477... = log 3/log 10. - Charles R Greathouse IV, Jul 22 2012
CROSSREFS
KEYWORD
nonn,base,easy
AUTHOR
Jonathan Vos Post, Jul 21 2012
STATUS
approved