A039641 -id:A039641 - cp's OEIS frontend

A039645 Number of steps to fixed point of "k -> k/2 or (k+1)/2 until result is prime", starting with prime(n)+1.

1, 2, 2, 3, 3, 2, 3, 3, 4, 5, 5, 2, 3, 3, 5, 4, 6, 2, 3, 5, 2, 5, 4, 3, 4, 4, 4, 5, 5, 3, 7, 4, 6, 6, 4, 4, 2, 3, 5, 5, 4, 4, 7, 2, 5, 5, 3, 6, 4, 4, 3, 8, 3, 8, 5, 5, 5, 5, 2, 3, 3, 4, 7, 7, 2, 7, 3, 4, 6, 6, 3, 5, 5, 4, 8, 8, 6, 2, 3, 3, 4, 2, 7, 3, 7, 7, 3, 2, 5, 5, 4, 9, 4, 5, 9, 9, 9, 3, 3, 2, 3, 8

Offset: 1

Wouter Meeussen

nonn

Reinhard Zumkeller, Table of n, a(n) for n = 1..10000

Cf. A039634-A039644.

Cf. A010051, A000040, A039641, A039643, A039637.

a039645 n = snd $ until ((== 1) . a010051 . fst)
            (\(x, i) -> ((x + 1) `div` 2 , i + 1)) (a000040 n + 1, 1)
-- Reinhard Zumkeller, Nov 17 2013

f[k_] := Which[PrimeQ[k], k, EvenQ[k], k/2, True, (k+1)/2];
a[n_] := Length[FixedPointList[f, Prime[n] + 1]] - 1;
Array[a, 102] (* Jean-François Alcover, Mar 01 2019 *)

Offset corrected by Reinhard Zumkeller, Nov 17 2013

A039635 Fixed point of "n -> n/2 or (n+1)/2 until result is prime".

Original entry on oeis.org

1, 2, 3, 2, 5, 3, 7, 2, 5, 5, 11, 3, 13, 7, 2, 2, 17, 5, 19, 5, 11, 11, 23, 3, 13, 13, 7, 7, 29, 2, 31, 2, 17, 17, 5, 5, 37, 19, 5, 5, 41, 11, 43, 11, 23, 23, 47, 3, 13, 13, 13, 13, 53, 7, 7, 7, 29, 29, 59, 2, 61, 31, 2, 2, 17, 17, 67, 17, 5, 5, 71, 5, 73, 37, 19, 19, 5, 5, 79, 5, 41

Offset: 1

Wouter Meeussen

nonn

Reinhard Zumkeller, Table of n, a(n) for n = 1..10000

Cf. A039634-A039645.

Cf. A010051, A039637, A039634, A039640, A039641.

a039635 1 = 1
a039635 n = until ((== 1) . a010051) ((flip div 2) . (+ 1)) n
-- Reinhard Zumkeller, Nov 17 2013

upp[ n_Integer ] := FixedPoint[ If[ EvenQ[ # ]&&#>2, #/2, If[ PrimeQ[ # ]||(#=== 1), #, (#+1)/2 ] ]&, n, 20 ]

Offset corrected by Reinhard Zumkeller, Nov 17 2013

A039639 Fixed point of "k -> k/2 or (k-1)/2 until result is prime", starting with prime(n)+1.

Original entry on oeis.org

3, 2, 3, 2, 3, 7, 2, 5, 3, 7, 2, 19, 5, 11, 3, 13, 7, 31, 17, 2, 37, 5, 5, 11, 3, 3, 13, 13, 13, 7, 2, 2, 17, 17, 37, 19, 79, 41, 5, 43, 11, 11, 3, 97, 3, 3, 53, 7, 7, 7, 29, 7, 7, 31, 2, 2, 67, 17, 139, 17, 71, 73, 19, 19, 157, 79, 83, 5, 43, 43, 11, 11, 23, 23, 47, 3, 97, 199, 3

Offset: 1

Wouter Meeussen

nonn

Reinhard Zumkeller, Table of n, a(n) for n = 1..10000

Cf. A039634-A039645.

Cf. A010051, A000040, A039643, A039641, A039634.

a039639 = until ((== 1) . a010051) (flip div 2) . (+ 1) . a000040
-- Reinhard Zumkeller, Nov 17 2013

Mathematica
```
(* See A039634. *)
```

Offset corrected by Reinhard Zumkeller, Nov 17 2013

cp's OEIS Frontend

A039645 Number of steps to fixed point of "k -> k/2 or (k+1)/2 until result is prime", starting with prime(n)+1.

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A039635 Fixed point of "n -> n/2 or (n+1)/2 until result is prime".

Views

Author

Keywords

Links

Crossrefs

Programs

Haskell

Mathematica

Extensions

A039639 Fixed point of "k -> k/2 or (k-1)/2 until result is prime", starting with prime(n)+1.

Views

Author

Keywords

Links

Crossrefs

Programs

Haskell

Mathematica

Extensions