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 A176982 Sequence defined by the recursion a(n) = (1/2)*((1-signum(abs(b(n))-n))*b(n)+(1+signum(abs(b(n))-n))*a(n-1)), with a(1)=1 and b(n)=1+a(n-1-(n mod a(n-1)))-(-1)^n*a(n-1). 1
 1, 1, 2, 1, 3, 1, 3, 1, 3, -1, -1, 1, 3, -3, -5, 3, 1, 1, 3, -1, -1, 1, 3, 1, 3, 1, 3, -1, -1, 1, 3, -3, -5, 5, 11, -13, -9, 21, 21, -21, -21, 1, 3, -23, -21, 1, 3, 1, 3, 1, 3, -1, -1, 1, 3, -3, -5, 7, 11, -9, -9, 9, 19, -21, -11, 1, 3, -13, -33, 23, 11, -21, -11, 1, 3, -1, -1, 1, 3, -3 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,3 COMMENTS Behaves erratically (see linked picture). There is a similar sequence with a(1)=2. REFERENCES G. Balzarotti and P. P. Lava, 103 curiosità matematiche, Hoepli, 2010, p. 276. LINKS Paolo P. Lava, Table of n, a(n) for n = 1..10000 Paolo P. Lava, Graph of the first 600 terms of the sequence John A. Pelesko, Generalizing the Conway-Hofstadter \$10,000 Sequence, Journal of Integer Sequences, Vol. 7 (2004), Article 04.3.5. Klaus Pinn, A Chaotic Cousin Of Conway's Recursive Sequence, arXiv:cond-mat/9808031, 1998. FORMULA a(n) = (1/2)*((1-signum(abs(b(n))-n))*b(n)+(1+signum(abs(b(n))-n))*a(n-1)), with a(1)=1 and b(n)=1+a(n-1-(n mod a(n-1)))-(-1)^n*a(n-1). EXAMPLE a(1)=1. b(2)=signum(abs(1+(2-1-(2 mod 1))-(-1)^2*1)-2)=signum(abs(1+1-1)-2)=-1. a(2)=(1/2)*(1+1)*1+(1/2)*(1-1)*1=1+0=1. MAPLE P:=proc(i) local a, n; a:=array(1..50000); a[1]:=1; print(a[1]); for n from 2 by 1 to i do a[n]:=1/2*(1-signum(abs(1+a[n-1-(n mod (a[n-1]))]-(-1)^n*a[n-1])-n))*(1+a[n-1-(n mod (a[n-1]))]-(-1)^n*a[n-1])+1/2*(1+signum(abs(1+a[n-1-(n mod (a[n-1]))]-(-1)^n*a[n-1])-n))*a[n-1]; print(a[n]); od; end: P(10000); CROSSREFS Cf. A004001, A176075, A176076. Sequence in context: A328049 A328050 A335620 * A079728 A181801 A029244 Adjacent sequences:  A176979 A176980 A176981 * A176983 A176984 A176985 KEYWORD sign,look AUTHOR Paolo P. Lava and Giorgio Balzarotti, Apr 30 2010 EXTENSIONS Entries and formula corrected by Paolo P. Lava, May 04 2010 a(3) corrected by N. J. A. Sloane, Oct 02 2010 STATUS approved

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Last modified April 22 16:32 EDT 2021. Contains 343177 sequences. (Running on oeis4.)