OFFSET
0,1
COMMENTS
a(n) = #{j: LD-3(n,j)=1}, where LD-3 is the Levenshtein distance on ternary strings.
LINKS
Michael Gilleland, Levenshtein Distance. [It has been suggested that this algorithm gives incorrect results sometimes. - N. J. A. Sloane]
EXAMPLE
n=12: ternary representation of numbers at Levenshtein distance 1 from 12='110':
{10, 11, 100, 111, 112, 120, 210, 1010, 1100, 1101,
1102, 1110, 1120, 1210, 2110}, therefore a(12)=15.
n=42: ternary representation of numbers at Levenshtein distance 1 from 42='1120':
{110, 112, 120, 1020, 1100, 1110, 1121, 1122, 1220,
2120, 10120, 11020, 11120, 11200, 11201, 11202, 11210, 11220, 12120, 21120},
therefore a(42)=20.
CROSSREFS
KEYWORD
nonn,base
AUTHOR
Reinhard Zumkeller, Apr 06 2003
STATUS
approved