This site is supported by donations to The OEIS Foundation.

 Hints (Greetings from The On-Line Encyclopedia of Integer Sequences!)
 A290079 Characteristic function for A249721: a(n) = 1 if there are either no 1-digits at all in base-3 representation of n, or if there are exactly two 1's next to each other, a(n) = 0 in any other cases. 3
 1, 0, 1, 0, 1, 0, 1, 0, 1, 0, 0, 0, 1, 0, 1, 0, 0, 0, 1, 0, 1, 0, 1, 0, 1, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 1, 0, 0, 0, 1, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 1, 0, 1, 0, 1, 0, 1, 0, 0, 0, 1, 0, 1, 0, 0, 0, 1, 0, 1, 0, 1, 0, 1, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 1, 0, 0, 0, 1, 0, 1, 0, 0, 0, 0 (list; graph; refs; listen; history; text; internal format)
 OFFSET 0 LINKS Antti Karttunen, Table of n, a(n) for n = 0..59049 FORMULA If n is even and 9 ∤ C(n,n/2), then a(n) = 1, otherwise a(n) = 0. EXAMPLE n A007089(n) a(n) = 1 if 1-free, except for possibly a single 11-pair,                        0 otherwise   ------------------    0    0         1    1    1         0    2    2         1    3   10         0    4   11         1    5   12         0    6   20         1    7   21         0    8   22         1    9  100         0   10  101         0   11  102         0   12  110         1   13  111         0   14  112         1   15  120         0 PROG (PARI) A290079(n) = if((!(n%2)&&(binomial(n, n/2)%9)), 1, 0); (Scheme) (define (A290079 n) (if (in_A249721? n) 1 0)) ;; See under A249721 for in_A249721? CROSSREFS Cf. A007089, A051382, A249721, A290093. Sequence in context: A014269 A014229 A014149 * A011632 A015157 A015213 Adjacent sequences:  A290076 A290077 A290078 * A290080 A290081 A290082 KEYWORD nonn,base AUTHOR Antti Karttunen, Jul 25 2017 STATUS approved

Lookup | Welcome | Wiki | Register | Music | Plot 2 | Demos | Index | Browse | More | WebCam
Contribute new seq. or comment | Format | Style Sheet | Transforms | Superseeker | Recent
The OEIS Community | Maintained by The OEIS Foundation Inc.

Last modified October 18 15:41 EDT 2019. Contains 328162 sequences. (Running on oeis4.)