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A087793 Least k such that S^k(n)=n^2 where S(x)=n*ceiling(sqrt(x)). 0
0, 2, 3, 4, 4, 4, 5, 5, 5, 5, 6, 6, 6, 6, 7, 7, 6, 7, 7, 7, 7, 7, 7, 7, 7, 7, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 10, 10, 10, 10, 10, 10, 10, 10, 10, 10, 10, 10, 10, 10, 10, 10, 10, 10, 10, 10, 10, 10 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,2

COMMENTS

For all m>k, S^m(n)=n^2

LINKS

Table of n, a(n) for n=0..93.

FORMULA

a(n)=sqrt(n)+o(sqrt(n))

PROG

(PARI) a(n)=if(n<0, 0, z=1; c=0; while(abs(z-n^2)>0, z=n*ceil(sqrt(z)); c++); c)

CROSSREFS

Sequence in context: A305233 A130242 A130245 * A030411 A194817 A211675

Adjacent sequences:  A087790 A087791 A087792 * A087794 A087795 A087796

KEYWORD

nonn

AUTHOR

Benoit Cloitre, Oct 07 2003

STATUS

approved

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Last modified June 28 17:10 EDT 2022. Contains 354907 sequences. (Running on oeis4.)