OFFSET
0,2
COMMENTS
In order to find a closed formula for A264847, this sequence could be useful to point out the terms in which the increment changes. For example, the increment is (a(i) + 3) from the 13th to the 31st, (a(i) + 4) from the 32nd to the 81st, etc.
Conjecture: lim_{n -> infinity} a(n)/a(n-1) = sqrt(10).
LINKS
Francesco Di Matteo, Table of n, a(n) for n = 0..100
EXAMPLE
MATHEMATICA
a = {0}; Do[AppendTo[a, a[[n - 1]] + Length@ Flatten@ Map[IntegerDigits, a]], {n, 2, 2000}]; Prepend[Most@ Map[Last, Tally[{1}~Join~IntegerLength@ Rest@ a]], 0] (* Michael De Vlieger, Dec 02 2015 *)
PROG
(Python)
a, b, d = 0, 0, 0
for g in range(1, 18):
h = 10**g
while a < h:
b = b + g
a = a + b
d = d + 1
print d
d = 0
CROSSREFS
KEYWORD
nonn,base
AUTHOR
Francesco Di Matteo, Dec 01 2015
STATUS
approved