login
The OEIS Foundation is supported by donations from users of the OEIS and by a grant from the Simons Foundation.

 

Logo


Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A256758 Position of first appearance of n in A256757. 2
1, 2, 3, 7, 19, 47, 163, 487, 1307, 2879, 19683, 59049, 177147, 531441, 1594323, 4782969, 14348907, 43046721, 86093443 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,2

COMMENTS

Smallest number m such that the trajectory of m under iteration of A007733 takes n steps to reach the fixed point.

The terms a(1)..a(9) are primes. The next eight terms are powers of 3, so that for n=10..17, a(n)=3^(n-1), but this apparently established pattern breaks at a(18), which is again a prime.

LINKS

Table of n, a(n) for n=0..18.

MATHEMATICA

A007733 = Function[n, MultiplicativeOrder[2, n/(2^IntegerExponent[n, 2])]];

A256757 = Function[n, k = 0; m = n; While[m > 1, m = A007733[m]; k++]; k];

a = Function[n, t = 1; While[A256757[t] < n , t++]; t]; Table[a[n], {n, 0, 9}] (* Ivan Neretin, Apr 13 2015 *)

PROG

(PARI) a007733(n) = znorder(Mod(2, n/2^valuation(n, 2)));

a256757(n) = {if (n==1, return(0)); nb = 1; while((n = a007733(n)) != 1, nb++); nb; }

a(n) = {k = 1; while(a256757(k) != n, k++); k; } \\ Michel Marcus, Apr 11 2015

(Haskell)

import Data.List (elemIndex); import Data.Maybe (fromJust)

a256758 = (+ 1) . fromJust . (`elemIndex`  a256757_list)

-- Reinhard Zumkeller, Apr 13 2015

CROSSREFS

Cf. A007733, A007755 (similarly built upon the totient function), A173927 (similarly built upon the Carmichael lambda function).

Sequence in context: A229290 A246033 A122724 * A033844 A037028 A052919

Adjacent sequences:  A256755 A256756 A256757 * A256759 A256760 A256761

KEYWORD

nonn,more

AUTHOR

Ivan Neretin, Apr 09 2015

EXTENSIONS

a(15)-a(18) from Michel Marcus, Apr 11 2015

STATUS

approved

Lookup | Welcome | Wiki | Register | Music | Plot 2 | Demos | Index | Browse | More | WebCam
Contribute new seq. or comment | Format | Style Sheet | Transforms | Superseeker | Recent
The OEIS Community | Maintained by The OEIS Foundation Inc.

License Agreements, Terms of Use, Privacy Policy. .

Last modified April 1 04:15 EDT 2020. Contains 333155 sequences. (Running on oeis4.)