A131881 Complement of A116700. Might be called "punctual birds".

1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 13, 14, 15, 16, 17, 18, 19, 20, 22, 24, 25, 26, 27, 28, 29, 30, 33, 35, 36, 37, 38, 39, 40, 44, 46, 47, 48, 49, 50, 55, 57, 58, 59, 60, 66, 68, 69, 70, 77, 79, 80, 88, 90, 100, 102, 103, 104, 105, 106, 107, 108, 109, 113, 114

Offset: 1

Author

M. F. Hasler, Jul 23 2007

Keywords

• nonn
• base
• easy

Comments

Numbers n that do not occur in the concatenation of 1,2,3...,n-1.

Every power of 10 is a member, which proves that the sequence is infinite. - N. J. A. Sloane, Jul 23 2007

The asymptotic density of the sequence is zero. The number of k-digit terms is A132133 = (9, 45, 270, 2104, ...), k = 1, 2, .... These are the first difference of the indices of powers of 10, T = (1, 10, 55, 325, 2429, ...), which we get as partial sums if we prefix A132133(0) = 1 corresponding to the number 0. - M. F. Hasler, Oct 24 2019

Examples

			The first number not in this sequence is the early bird "12" which occurs as concatenation of 1 and 2.
		

Links

• M. F. Hasler, Table of n, a(n) for n = 1..2428

Crossrefs

Cf. A116700 (early birds), A132133 (number of n-digit terms).

Cf. A007376 (Barbier word ...,8,9,1,0,1,1,...), A033307 (Champernowne constant).

Programs

PHP

$s="0"; for(; ++$i < 2000; $s .= $i) if( !strpos($s,"$i")) echo $i,", ";