OFFSET
1,2
COMMENTS
The sequence is periodic: a(470) = a(312) = 8005, etc.
See A235460 for the analogous sequence where we number the digits starting with 1 at the leftmost digit.
REFERENCES
Rodolfo Kurchan, Problems with repdigits, to appear in Proceedings of Gathering for Gardner 2014 conference
LINKS
Alois P. Heinz, Table of n, a(n) for n = 1..1000
EXAMPLE
1 leads to one 9, then 9 leads to 999999999, then we have to sum 111111111 + 222222222 + ... + 999999999 = 4999999995, then we have to sum 1111 + 222222222 + ... + 888888888 + 99999 = 4000099995, and so on.
MATHEMATICA
nxt[n_]:=Total[FromDigits/@(Table[#[[1]], {#[[2]]}]&/@Thread[{ Range[ 9, 10-IntegerLength[n], -1], Reverse[IntegerDigits[n]]}])]; NestList[ nxt, 1, 30] (* Harvey P. Dale, Apr 24 2015 *)
CROSSREFS
KEYWORD
nonn,base,nice
AUTHOR
Rodolfo Kurchan, Jan 09 2014
STATUS
approved