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A019300
First n elements of Thue-Morse sequence A010060 read as a binary number.
8
0, 1, 3, 6, 13, 26, 52, 105, 211, 422, 844, 1689, 3378, 6757, 13515, 27030, 54061, 108122, 216244, 432489, 864978, 1729957, 3459915, 6919830, 13839660, 27679321, 55358643, 110717286, 221434573, 442869146, 885738292, 1771476585, 3542953171
OFFSET
0,3
LINKS
FORMULA
a(0) = 0, a(n+1) = 2a(n) + A010060(n). - Ralf Stephan, Sep 16 2003
MATHEMATICA
With[{tm=Nest[Flatten[#/.{0->{0, 1}, 1->{1, 0}}]&, {0}, 7]}, Table[ FromDigits[ Take[tm, n], 2], {n, 40}]] (* Harvey P. Dale, Mar 25 2015 *)
PROG
(Scheme)
(define rdc(lambda(x)(if(null? (cdr x))'()(cons (car x) (rdc (cdr x))))))
; if a bit is 1, get 2^i, where i is the index of that bit from right-left
(define F (lambda (c i)(if (eq? c #\1) (expt 2 i) 0)))
; gathers the sum of 2^index for all indices corresponding to a 1
(define fn (lambda (x sum i stop)(if (eq? i stop) sum (fn (list->string (rdc (string->list x))) (+ sum (F (string-ref x (-(string-length x) 1)) i)) (+ i 1)stop))))
(define f (lambda (x)(fn (substring thue 0 (+ x 1)) 0 0 (string-length (substring thue 0 (+ x 1))) )))
(define thue "0110100110010110") ; Feel free to add Thue-Morse sequence of whatever length here
; Ariel S Koiman, May 07 2013
(PARI) a(n)=sum(k=1, n, (hammingweight(k)%2)<<(n-k)) \\ Charles R Greathouse IV, May 08 2016
(PARI) first(n)=my(v=vector(n)); v[1]=1; for(k=2, n, v[k]=2*v[k-1]+hammingweight(k)%2); concat(0, v) \\ Charles R Greathouse IV, May 08 2016
CROSSREFS
Cf. A010060, A048707, A320916 (bit reversal).
Sequence in context: A255125 A267367 A265385 * A072762 A081254 A125049
KEYWORD
nonn,easy
STATUS
approved