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 A117942 a(n) = a(3n) = -a(3n+1) = -a(3n+2)/2. 4
 1, -1, -2, -1, 1, 2, -2, 2, 4, -1, 1, 2, 1, -1, -2, 2, -2, -4, -2, 2, 4, 2, -2, -4, 4, -4, -8, -1, 1, 2, 1, -1, -2, 2, -2, -4, 1, -1, -2, -1, 1, 2, -2, 2, 4, 2, -2, -4, -2, 2, 4, -4, 4, 8, -2, 2, 4, 2, -2, -4, 4, -4, -8, 2, -2, -4, -2, 2, 4, -4, 4, 8, 4, -4, -8, -4, 4, 8, -8, 8, 16, -1, 1, 2, 1, -1, -2, 2, -2, -4, 1, -1 (list; graph; refs; listen; history; text; internal format)
 OFFSET 0,3 COMMENTS a(n) = a(3n)/a(0) = a(3n+1)/a(1) = a(3n+2)/a(2). Row sums of A117941. LINKS Antti Karttunen, Table of n, a(n) for n = 0..19683 FORMULA a(n) = 2^A081603(n) * (-1)^(A062756(n)+A081603(n)). - Antti Karttunen, Jul 26 2017 PROG (Scheme) ;; A stand-alone recurrence: (define (A117942 n) (cond ((zero? n) 1) ((zero? (modulo n 3)) (A117942 (/ n 3))) (else (let ((d (modulo n 3))) (- (* d (A117942 (/ (- n d) 3)))))))) ;; An implementation based on a new formula: (Scheme) (define (A117942 n) (* (A000079 (A081603 n)) (expt -1 (+ (A062756 n) (A081603 n))))) ;; Antti Karttunen, Jul 26 2017 CROSSREFS Cf. A117592 (gives the absolute values). Cf. A062756, A081603. Sequence in context: A145788 A323861 A117592 * A290092 A066877 A240071 Adjacent sequences:  A117939 A117940 A117941 * A117943 A117944 A117945 KEYWORD sign AUTHOR Paul Barry, Apr 05 2006 EXTENSIONS More terms from Antti Karttunen, Jul 26 2017 STATUS approved

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Last modified October 15 00:14 EDT 2019. Contains 328025 sequences. (Running on oeis4.)