A103847 McCarthy's 91 Function: a(n) = n-10 if n>100, otherwise a(n) = a(a(n+11)).

91, 91, 91, 91, 91, 91, 91, 91, 91, 91, 91, 91, 91, 91, 91, 91, 91, 91, 91, 91, 91, 91, 91, 91, 91, 91, 91, 91, 91, 91, 91, 91, 91, 91, 91, 91, 91, 91, 91, 91, 91, 91, 91, 91, 91, 91, 91, 91, 91, 91, 91, 91, 91, 91, 91, 91, 91, 91, 91, 91, 91, 91, 91, 91, 91, 91, 91, 91, 91, 91, 91, 91, 91, 91, 91, 91, 91, 91, 91, 91, 91, 91, 91, 91, 91, 91, 91, 91, 91, 91, 91, 91, 91, 91, 91, 91, 91, 91, 91, 91, 91, 92, 93, 94, 95, 96, 97, 98, 99, 100, 101, 102, 103, 104, 105, 106, 107, 108, 109, 110, 111, 112, 113, 114, 115, 116, 117, 118, 119, 120, 121, 122, 123, 124, 125, 126, 127, 128, 129, 130, 131, 132, 133, 134

Offset

1,1

Comments

Takes the value 91 for 1<=n<=101. First term that is not 91 is a(102)=92.

References

J. C. Lagarias, ed., The Ultimate Challenge: The 3x+1 Problem, Amer. Math. Soc., 2010. See p. 302.

Links

Table of n, a(n) for n=1..144.

Eric Weisstein's World of Mathematics, McCarthy 91-Function

Index entries for sequences related to 3x+1 (or Collatz) problem

Maple

F:=proc(n) option remember;
if n > 100 then n-10 else F(F(n+11)); fi; end;

Crossrefs

Sequence in context: A329915 A087411 A203363 * A043585 A043780 A043790

Adjacent sequences: A103844 A103845 A103846 * A103848 A103849 A103850

Keyword

nonn

Author

Eric W. Weisstein, Feb 17 2005

Extensions

Edited by and more terms from N. J. A. Sloane, Jan 31 2011

Status

approved