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A324964
a(n) = A000139(n) mod 2; Characteristic function of odd fibbinary numbers (A022341).
4
0, 1, 0, 0, 0, 1, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 1, 0, 0, 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, 1, 0, 0, 0, 1, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0
OFFSET
0
COMMENTS
Equals 1 if and only if the binary expansion of n does not contain two 1's in consecutive positions and ends in a 1.
FORMULA
a(n) = A000035(n)*A085357(n) = A000035(n)*A008966(A005940(1+n)). - Antti Karttunen, Aug 22 2019
MATHEMATICA
Table[Mod[2/((n + 1) (2 n + 1)) Binomial[3 n, n], 2], {n, 0, 100}]
PROG
(PARI) a(n)=binomial(3*n, n)*2/((n+1)*(2*n+1)) % 2; \\ Michel Marcus, Apr 02 2019
(PARI) A324964(n) = ((n%2)&&!bitand(n, n<<1)); \\ Antti Karttunen, Aug 22 2019
CROSSREFS
Characteristic function of A022341.
Sequence in context: A122415 A241666 A324539 * A285957 A292273 A324772
KEYWORD
nonn
AUTHOR
Colin Defant, Mar 21 2019
EXTENSIONS
Secondary name and more terms added by Antti Karttunen, Aug 22 2019
STATUS
approved