cp's OEIS Frontend

This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.

A226195 Numbers n = x0 x1 x2...x9 such that xi is the number of digits greater than i in n.

Original entry on oeis.org

1, 10, 21, 22, 100, 210, 220, 311, 321, 332, 333, 1000, 2100, 2200, 3110, 3210, 3320, 3330, 4111, 4211, 4321, 4331, 4422, 4432, 4443, 4444, 10000, 21000, 22000, 31100, 32100, 33200, 33300, 41110, 42110, 43210, 43310, 44220, 44320, 44430, 44440, 51111, 52111
Offset: 1

Views

Author

Michel Lagneau, May 30 2013

Keywords

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 powers of 10 (A011557(0)..A011557(9)) are in the sequence.
The numbers of the form a(n)*10^p are also in the sequence.

Examples

			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.
		

Crossrefs

Programs

  • 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