The On-Line Encyclopedia of Integer Sequences (OEIS)

Revision History for A033959

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A033959

Record number of steps to reach 1 in '3x+1' problem, corresponding to starting values in A033958.
(history; published version)

#18 by Susanna Cuyler at Fri Apr 01 09:13:15 EDT 2022

STATUS

proposed

approved

#17 by Michel Marcus at Fri Apr 01 04:04:37 EDT 2022

STATUS

editing

proposed

#16 by Michel Marcus at Fri Apr 01 04:04:34 EDT 2022

REFERENCES

B. Hayes, Computer Recreations: On the ups and downs of hailstone numbers, Scientific American, 250 (No. 1, 1984), pp. 10-16.

LINKS

Brian Hayes, <a href="https://www.jstor.org/stable/24969271">Computer Recreations: On the ups and downs of hailstone numbers</a>, Scientific American, 250 (No. 1, 1984), pp. 10-16.

STATUS

approved

editing

#15 by Susanna Cuyler at Sun Oct 20 22:03:43 EDT 2019

STATUS

proposed

approved

#14 by Jon E. Schoenfield at Sun Oct 20 21:50:14 EDT 2019

STATUS

editing

proposed

#13 by Jon E. Schoenfield at Sun Oct 20 21:50:12 EDT 2019

NAME

Record number of steps to reach 1 in `'3x+1' problem, corresponding to starting values in A033958.

COMMENTS

Only the 3x+1 steps , not the halving steps , are counted.

AUTHOR

N. J. A. Sloane.

EXTENSIONS

More terms from Winston C. Yang (winston(AT)cs.wisc.edu), Aug 27 2000 and from Larry Reeves (larryr(AT)acm.org), Sep 27 2000

More terms from Larry Reeves (larryr(AT)acm.org), Sep 27 2000

STATUS

approved

editing

#12 by Reinhard Zumkeller at Thu Jan 09 01:24:08 EST 2014

STATUS

editing

approved

#11 by Reinhard Zumkeller at Wed Jan 08 16:39:28 EST 2014

PROG

(Haskell)

a033959 n = a033959_list !! (n-1)

(a033959_list, a033958_list) = unzip $ (0, 1) : f 1 1 where

f i x | y > x = (y, 2 * i - 1) : f (i + 1) y

| otherwise = f (i + 1) x

where y = a075680 i

-- Reinhard Zumkeller, Jan 08 2014

CROSSREFS

Cf. A075680.

#10 by Reinhard Zumkeller at Wed Jan 08 16:37:48 EST 2014

OFFSET

0,1,2

EXTENSIONS

Offset corrected by Reinhard Zumkeller, Jan 08 2014

STATUS

approved

editing

#9 by Russ Cox at Fri Mar 30 16:47:26 EDT 2012

AUTHOR

_N. J. A. Sloane (njas(AT)research.att.com)_.

Discussion

Fri Mar 30

16:47

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