A033023 Numbers whose base-10 expansion has no run of digits with length < 2.

11, 22, 33, 44, 55, 66, 77, 88, 99, 111, 222, 333, 444, 555, 666, 777, 888, 999, 1100, 1111, 1122, 1133, 1144, 1155, 1166, 1177, 1188, 1199, 2200, 2211, 2222, 2233, 2244, 2255, 2266, 2277, 2288, 2299, 3300, 3311, 3322, 3333

Offset: 1

Author

Clark Kimberling

Keywords

• nonn
• base

Comments

Contains A014181 as subsequence. A115853 is a supersequence. - M. F. Hasler, Jun 24 2016

Links

• Giovanni Resta, Table of n, a(n) for n = 1..10000 (first 1100 terms from Vincenzo Librandi)
• Giovanni Resta, Zygodrome

Crossrefs

Cf. A014181, A115853.

Programs

Mathematica

Select[Range[10000], Min[Length/@Split[IntegerDigits[#, 10]]]>1&] (* Vincenzo Librandi, Feb 05 2014 *)

PARI

is(n)={n=digits(n);while(#n>2 && n[2]==n[1], n=if(n[3]==n[1],n[^1],n[3..-1]));#n>1&&n[1]==n[2]} \\ M. F. Hasler, Jun 24 2016