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A025586 Largest value in `3x+1' trajectory of n. 45
1, 2, 16, 4, 16, 16, 52, 8, 52, 16, 52, 16, 40, 52, 160, 16, 52, 52, 88, 20, 64, 52, 160, 24, 88, 40, 9232, 52, 88, 160, 9232, 32, 100, 52, 160, 52, 112, 88, 304, 40, 9232, 64, 196, 52, 136, 160, 9232, 48, 148, 88, 232, 52, 160, 9232, 9232, 56, 196, 88, 304, 160, 184, 9232 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

COMMENTS

a(n) = A220237(n,A006577(n)). - Reinhard Zumkeller, Jan 03 2013

A006885 and A006884 give record values and where they occur. - Reinhard Zumkeller, May 11 2013

LINKS

T. D. Noe, Table of n, a(n) for n=1..10000

P. Picart, Algorithme de Collatz et conjecture de Syracuse

Index entries for sequences related to 3x+1 (or Collatz) problem

MATHEMATICA

Collatz[a0_Integer, maxits_:1000] := NestWhileList[If[EvenQ[ # ], #/2, 3# + 1] &, a0, Unequal[ #, 1, -1, -10, -34] &, 1, maxits]; (* Collatz[n] function definition by Eric Weisstein *) Flatten[Table[Take[Sort[Collatz[n], Greater], 1], {n, 60}]] (* Alonso del Arte, Nov 14 2007 *)

a[n_] := Module[{r=m=n}, While[m>2, If[OddQ[m], m=3*m+1; If[m>r, r=m], m=m/2]]; r]; Table[a[n], {n, 1, 100}] (* Jean-Fran├žois Alcover, Jan 28 2015, after Charles R Greathouse IV *)

PROG

(PARI) a(n)=my(r=n); while(n>2, if(n%2, n=3*n+1; if(n>r, r=n), n/=2)); r \\ Charles R Greathouse IV, Jul 19 2011

(Haskell)

a025586 = last . a220237_row

-- Reinhard Zumkeller, Jan 03 2013, Aug 29 2012

(Python)

def a(n):

    if n<2: return 1

    l=[n, ]

    while True:

        if n%2==0: n/=2

        else: n = 3*n + 1

        if not n in l:

            l+=[n, ]

            if n<2: break

        else: break

    return max(l)

print [a(n) for n in xrange(1, 101)] # Indranil Ghosh, Apr 14 2017

CROSSREFS

Essentially the same as A056959.

Cf. A006370.

Sequence in context: A076536 A110009 A232503 * A087251 A211367 A220314

Adjacent sequences:  A025583 A025584 A025585 * A025587 A025588 A025589

KEYWORD

nonn,nice,look

AUTHOR

David W. Wilson

STATUS

approved

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Last modified September 25 19:48 EDT 2017. Contains 292500 sequences.