The On-Line Encyclopedia of Integer Sequences (OEIS)

Revision History for A046075

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A046075

Nontrivial undulants; base 10 numbers >100 which are of the form aba, abab, ababa, ..., where a != b.
(history; published version)

#21 by Reinhard Zumkeller at Wed Apr 29 19:25:04 EDT 2015

STATUS

editing

approved

#20 by Reinhard Zumkeller at Wed Apr 29 16:33:11 EDT 2015

PROG

where f s = m : f (insert z (10 * m + div (mod m 100) 10) s')

where z = 10 * m + div (mod m 100) 10

where (m, s') = deleteFindMin s

STATUS

approved

editing

#19 by Reinhard Zumkeller at Wed Apr 29 16:23:54 EDT 2015

STATUS

editing

approved

#18 by Reinhard Zumkeller at Wed Apr 29 16:18:48 EDT 2015

PROG

a046075_list = f $ fromList $ [10..99] \\ [11, 22, 33, 44, 55, 66, 77, 88, 99]

a046075_list = f $ fromList

[100 * a + 10 * b + a | a <- [1..9], b <- [0..9], b /= a]

where f s | = m < 100 = : f (insert (m * 10 + h) z s')

| otherwise = m : f (insert (m * 10 + h) s')

where h z = 10 * m + div (mod m 100) 10

(m, s') = deleteFindMin s

-- Reinhard Zumkeller, Apr 29 2015, May 01 2012

CROSSREFS

Cf. A252664.

STATUS

approved

editing

#17 by Charles R Greathouse IV at Wed Apr 22 17:19:13 EDT 2015

STATUS

proposed

approved

#16 by Danny Rorabaugh at Wed Apr 22 14:53:14 EDT 2015

STATUS

editing

proposed

#15 by Danny Rorabaugh at Wed Apr 22 14:52:20 EDT 2015

NAME

Nontrivial undulants; base 10 numbers >100 which are of the form aba, abab, ababa, ..., where a != b.

CROSSREFS

Cf. A046076, A033619, A046076.

STATUS

approved

editing

Discussion

Wed Apr 22

14:53

Danny Rorabaugh: Changed a!=b to a != b to prevent confusion with a! = b.

#14 by Charles R Greathouse IV at Sat Jul 13 12:02:06 EDT 2013

LINKS

_Reinhard Zumkeller_, , <a href="/A046075/b046075.txt">Table of n, a(n) for n = 1..10000</a>

Discussion

Sat Jul 13

12:02

OEIS Server: https://oeis.org/edit/global/1934

#13 by N. J. A. Sloane at Fri Feb 22 21:36:55 EST 2013

LINKS

_Reinhard Zumkeller, _, <a href="/A046075/b046075.txt">Table of n, a(n) for n = 1..10000</a>

Discussion

Fri Feb 22

21:36

OEIS Server: https://oeis.org/edit/global/1866

#12 by Charles R Greathouse IV at Thu Oct 11 10:14:07 EDT 2012

LINKS

C. A. Pickover, "Wonders of Numbers, Adventures in Mathematics, Mind and Meaning," <a href="http://www.emis.de/cgizentralblatt-bin/zmenmath.org/ZMATHzmath/en/quick.htmlsearch/?first=1&maxdocs=3&typeq=html&an=:0983.00008&format=complete">Zentralblatt review</a>

Discussion

Thu Oct 11

10:14

OEIS Server: https://oeis.org/edit/global/1834