OFFSET
1,3
COMMENTS
Write the natural numbers as an infinite sequence of digits, starting at the left; and count the digits of each group of "1"'s you encounter (the smallest "groups" have one "1").
EXAMPLE
a(1)=1: the first "1" of the counting numbers, isolated.
a(2)=1: the second "1", first digit of number 10, isolated.
a(3)=3 two "1"'s of 11 and one "1" of 12 = three "1"'s, the next group of "1"'s.
CROSSREFS
KEYWORD
base,easy,nonn
AUTHOR
Alexandre Wajnberg, Mar 28 2005
STATUS
approved