OFFSET
1,1
COMMENTS
LINKS
Vincenzo Librandi, Table of n, a(n) for n = 1..250
FORMULA
a(n)=4*A043307(n). - M. F. Hasler, Feb 01 2014
MATHEMATICA
Select[Range[10000], Union[Length/@Split[IntegerDigits[#, 3]]]=={2}&] (* Vincenzo Librandi, Feb 05 2014 *)
PROG
From M. F. Hasler, Feb 01 2014 (Start)
(PARI) is_A033001(n)=!until(!n\=9, bittest(4588304, n%27)||return)
(PARI) for(n=1, 9999, is_A033001(n)&&print1(n", ")) \\ (End)
(PARI) a(n) = my(v=binary(n+1)); v[1]=0; for(i=2, #v, v[i]+=(v[i]>=v[i-1])); 4*fromdigits(v, 9); \\ Kevin Ryde, Mar 13 2021
CROSSREFS
KEYWORD
nonn,base
AUTHOR
STATUS
approved