A098752 a(1) = 1 and a(n+1) is the least number > a(n) that begins with the last digit of a(n) and doesn't end with 0.

1, 11, 12, 21, 101, 102, 201, 1001, 1002, 2001, 10001, 10002, 20001, 100001, 100002, 200001, 1000001, 1000002, 2000001, 10000001, 10000002, 20000001, 100000001, 100000002, 200000001, 1000000001, 1000000002, 2000000001, 10000000001

Offset

1,2

Comments

a(n) must be chosen with nonzero rightmost digit.

Links

Table of n, a(n) for n=1..29.

Formula

For n == 0 (mod 3), a(n) = 10^(n/3) + 2; for n == 1 (mod 3), n>1, a(n) = 2*10^((n-1)/3) + 1; for n == 2 (mod 3), a(n) = 10^((n+1)/3) + 1. - Sam Alexander, Jan 04 2005

From Chai Wah Wu, Jun 02 2016: (Start)

a(n) = 11*a(n-3) - 10*a(n-6) for n > 7.

G.f.: x*(1 + x + 2*x^2)*(1 + 10*x - 10*x^3 - 10*x^4)/((1 - x)*(1 - 10*x^3)*(1 + x + x^2)). (End)

a(n) = (1-sign((n-1) mod 3))*10^floor(n/3)+10^floor((n+1)/3)-sign(n mod 3)+2, for n > 1. - Wesley Ivan Hurt, Mar 06 2022

Crossrefs

Cf. A076654.

Cf. A101233.

Sequence in context: A131363 A089185 A098754 * A240763 A231871 A192287

Adjacent sequences: A098749 A098750 A098751 * A098753 A098754 A098755

Keyword

base,easy,nonn

Author

Eric Angelini, Oct 01 2004

Extensions

More terms from Sam Alexander, Jan 04 2005

More terms from David Wasserman, Feb 26 2008

Status

approved