

A190338


Consider the iteration k > 3*k mod 10^(number of decimal digits in n). Sequence gives the number of times the iteration has to be applied to n before returning to n.


1



1, 4, 4, 4, 4, 1, 4, 4, 4, 4, 4, 20, 20, 20, 20, 4, 20, 20, 20, 20, 4, 20, 20, 20, 20, 2, 20, 20, 20, 20, 4, 20, 20, 20, 20, 4, 20, 20, 20, 20, 4, 20, 20, 20, 20, 4, 20, 20, 20, 20, 1, 20, 20, 20, 20, 4, 20, 20, 20, 20, 4, 20, 20, 20, 20, 4, 20, 20, 20, 20
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OFFSET

0,2


COMMENTS

Pickover called a sequence of this type an "Odin sequence". It seems that a(n) = 4*5^(A055642(n)  1) whenever n mod 5 <> 0.


REFERENCES

Clifford A. Pickover, A Passion for Mathematics, Wiley, 2005; see p. 124.


LINKS

Nathaniel Johnston, Table of n, a(n) for n = 0..10000


MAPLE

a := proc(n) local c, k: c:=0:k:=n: do k:=3*k mod (10^length(n)):c:=c+1: if(k=n)then return c: fi: od: end: seq(a(n), n=0..150);


MATHEMATICA

Flatten[Table[Position[NestList[Mod[3#, 10^IntegerLength[n]]&, n, 40], n][[2]]1, {n, 0, 70}]] (* Harvey P. Dale, Mar 05 2013 *)


CROSSREFS

Cf. A055642.
Sequence in context: A171408 A071907 A172369 * A199177 A320086 A074803
Adjacent sequences: A190335 A190336 A190337 * A190339 A190340 A190341


KEYWORD

nonn,easy,base


AUTHOR

Nathaniel Johnston, May 09 2011


STATUS

approved



