OFFSET
1,2
COMMENTS
This sequence contains 1142 terms.
Extension of the autobiographical numbers (or curious numbers) (A046043).
The concatenated numbers from n down to 1 (A000422(1) - A000422(9)): 1, 21, 321, ..., 987654321 are in the sequence.
The sequence includes A000461(n) (the n-digit number consisting of all n's) for n=1..9, i.e., 1, 22, 333, 4444, ..., 999999999.
The numbers of the form a(n)*10^p are also in the sequence.
LINKS
Michel Lagneau, Table of n, a(n) for n = 1..1142
EXAMPLE
x0 x1 x2 x3 = 4211 is in the sequence because, for i = 0, 1, 2, 3:
xi > 0 (4 times) => x0 = 4;
xi > 1 (2 times) => x1 = 2;
xi > 2 (1 time) => x2 = 1;
xi > 3 (1 time) => x3 = 1.
MAPLE
T:=array(1..10):for n from 1 to 100000 do:nn:=length(n):for a from 1 to nn do:T[a] :=0:od:x:=convert(n, base, 10): for k from 1 to nn do:for i from 1 to nn do: if k-1<x[i] then T[k]:=T[k]+1:else fi:od:od: s:=sum('T[j]*10^(nn-j) ', 'j'=1..nn):if s=n then printf(`%d, `, n):else fi:od:
CROSSREFS
KEYWORD
nonn,base,fini,full
AUTHOR
Michel Lagneau, May 30 2013
STATUS
approved