A073261 Length of FixedPointList approximating (2^n)-th composite number. See program link below.

4, 4, 3, 3, 3, 4, 3, 5, 4, 4, 5, 4, 5, 6, 6, 6, 6, 5, 6, 6, 7, 6, 6, 6, 7, 7, 8, 7, 7, 8, 8, 8, 8, 8, 8, 8, 8, 9, 9, 9, 9, 9, 10, 10, 9, 10

Offset

0,1

Comments

Number of iterations needed to reach the composite number using the formula in the program.

Links

Table of n, a(n) for n=0..45.

Example

n=30: {1073741824, 1128141853, 1130754984, 1130880243, 1130886219, 1130886489, 1130886503, 1130886504}, so a(30)=8.

Mathematica

Table[ Length[ FixedPointList[ 2^n+PrimePi[ # ]+1 &, 2^n]]-1, {n, 0, 45}]

Crossrefs

Cf. A002808, A073255-A073264, A065856.

Sequence in context: A228777 A329205 A023402 * A209252 A265131 A344894

Adjacent sequences: A073258 A073259 A073260 * A073262 A073263 A073264

Keyword

nonn

Author

Labos Elemer, Jul 22 2002

Extensions

Extended by Robert G. Wilson v, Jul 24 2002

Status

approved