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.

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

Offset

0

Links

Antti Karttunen, Table of n, a(n) for n = 0..59049

Index entries for characteristic functions

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