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A283468
a(n) = A004001(A004001(n-1)) - A004001(n-A004001(n-1)), a(1) = a(2) = 1.
4
1, 1, 0, 0, -1, 0, 0, 0, -1, 0, 1, 1, 0, 0, 0, 0, -1, 0, 1, 2, 2, 1, 2, 2, 1, 1, 1, 0, 0, 0, 0, 0, -1, 0, 1, 2, 3, 3, 2, 3, 4, 4, 3, 4, 4, 3, 3, 3, 2, 3, 3, 2, 2, 2, 1, 1, 1, 1, 0, 0, 0, 0, 0, 0, -1, 0, 1, 2, 3, 4, 4, 3, 4, 5, 6, 6, 5, 6, 7, 7, 6, 7, 7, 6, 6, 6, 5, 6, 7, 7, 6, 7, 7, 6, 6, 6, 5, 6, 6, 5, 5, 5, 4, 4, 4, 4, 3, 4, 4, 3, 3, 3, 2, 2, 2, 2, 1, 1, 1, 1
OFFSET
1,20
COMMENTS
The only negative terms seem to be -1's, occurring as a(1+(2^n)), for n >= 2.
LINKS
FORMULA
a(1) = a(2) = 1; for n > 2, a(n) = A004001(A004001(n-1)) - A004001(A080677(n-1)).
MATHEMATICA
a[n_] := a[n] = If[n <= 2, 1, a[a[n - 1]] + a[n - a[n - 1]]]; Table[a[#] - a[n - #] &@ a[n - 1] + Boole[n <= 2], {n, 120}] (* Michael De Vlieger, Mar 18 2017, after Robert G. Wilson v at A004001 *)
PROG
(Scheme)
(define (A283468 n) (if (<= n 2) 1 (- (A004001 (A004001 (- n 1))) (A004001 (- n (A004001 (- n 1)))))))
;; Code for A004001 given under that entry.
CROSSREFS
Cf. A004001, A080677, A283471 (positions of zeros), A283469, A283470, A283472.
Cf. also A283655.
Sequence in context: A342870 A143537 A125916 * A100244 A059689 A334904
KEYWORD
sign
AUTHOR
Antti Karttunen, Mar 18 2017
STATUS
approved