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A145325 Least k such that f(n,k) is not a prime, where f(n,1)=2n+1 and f(n,k)=f(f(n,k-1)) for k>=2. 2
3, 5, 2, 1, 4, 2, 1, 2, 2, 1, 3, 1, 1, 3, 2, 1, 1, 2, 1, 4, 2, 1, 2, 1, 1, 3, 1, 1, 2, 2, 1, 1, 2, 1, 2, 2, 1, 1, 2, 1, 3, 1, 1, 5, 1, 1, 1, 2, 1, 2, 2, 1, 2, 2, 1, 3, 1, 1, 1, 1, 1, 1, 2, 1, 3, 1, 1, 2, 2, 1, 1, 1, 1, 2, 2, 1, 1, 2, 1, 1, 2, 1, 2, 1, 1, 3, 1, 1, 4, 2, 1, 1, 1, 1, 3, 2, 1, 2, 2, 1, 1, 1, 1, 1, 2 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

LINKS

Table of n, a(n) for n=1..105.

EXAMPLE

f(1,1)=3, f(1,2)=7, f(1,3)=15, so a(1)=3.

For n=1,2,3,4,5, the first few f's follow:

1: 3,7,15,31,63

2: 5,11,23,47,95

3: 7,15,31,63,127

4: 9,19,39,77,159

5: 11,23,47,95,191

CROSSREFS

Cf. A145326, A145327.

Sequence in context: A183206 A197521 A161865 * A282194 A126353 A094791

Adjacent sequences:  A145322 A145323 A145324 * A145326 A145327 A145328

KEYWORD

easy,nonn

AUTHOR

Clark Kimberling, Oct 07 2008

STATUS

approved

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Last modified April 24 04:00 EDT 2019. Contains 322406 sequences. (Running on oeis4.)