OFFSET
1,1
COMMENTS
"Valid substrings" means all numbers that appear as substring of n (written in decimal system). Starting values < 10 would yield a constant sequence.
LINKS
E. Angelini, Sum of all valid substrings (VS), SeqFan list, Jan 16 2009
EXAMPLE
a(1) = 10 has { 0, 1, 10 } as distinct substrings,
a(2) = 0+1+10 = 11 has { 1, 11 } as distinct substrings,
a(3) = 1+11 = 12 has { 1, 2, 12 } as distinct substrings,
a(4) = 1+2+12 = 15 has { 1, 5, 15 } as distinct substrings.
PROG
CROSSREFS
KEYWORD
base,easy,nonn
AUTHOR
Eric Angelini and M. F. Hasler, Jan 16 2009
EXTENSIONS
The word "distinct" added to definition Jan 19 2009 at the suggestion of Hugo van der Sanden.
STATUS
approved