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Revision History for A060979

(Bold, blue-underlined text is an addition; faded, red-underlined text is a ~~deletion~~.)
Showing entries 1-10 | older changes

A060979

|First digit - second digit + third digit - fourth digit ...| = 11.
(history; published version)

#16 by Michael De Vlieger at Fri Jun 02 15:20:48 EDT 2023

STATUS

reviewed

approved

#15 by Robert C. Lyons at Fri Jun 02 13:54:49 EDT 2023

STATUS

proposed

reviewed

#14 by Jon E. Schoenfield at Fri Jun 02 13:30:53 EDT 2023

STATUS

editing

proposed

#13 by Jon E. Schoenfield at Fri Jun 02 13:30:50 EDT 2023

COMMENTS

Note that all entries terms are divisible by eleven.

STATUS

proposed

editing

#12 by Robert Israel at Fri Jun 02 13:09:40 EDT 2023

STATUS

editing

proposed

#11 by Robert Israel at Fri Jun 02 13:09:36 EDT 2023

EXTENSIONS

Erroneous comment deleted by Robert Israel, Jun 02 2023

STATUS

proposed

editing

#10 by Robert Israel at Fri Jun 02 13:09:05 EDT 2023

STATUS

editing

proposed

#9 by Robert Israel at Fri Jun 02 13:06:49 EDT 2023

COMMENTS

Also multiples of 11 such that the sum of digits at odd positions is different from sum of digits at even positions; cf. A135499. - Reinhard Zumkeller, Jul 05 2014

MAPLE

filter:= proc(n) local L, i;

L:= convert(n, base, 10);

abs(add(L[i]*(-1)^i, i=1..nops(L))) = 11

end proc:

select(filter, [$1..1000] *~ 11); # Robert Israel, Jun 02 2023

STATUS

approved

editing

Discussion

Fri Jun 02

13:09

Robert Israel: Zumkeller's comment was not true.  For example, 40909 is not a term despite being a multiple of 11 whose sum of digits at odd positions and sum of digits at even positions are different.

#8 by Reinhard Zumkeller at Sat Jul 05 13:03:37 EDT 2014

STATUS

editing

approved

#7 by Reinhard Zumkeller at Sat Jul 05 12:14:12 EDT 2014

COMMENTS

Also multiples of 11 such that the sum of digits at odd positions is different from sum of digits at even positions; cf. A135499. - Reinhard Zumkeller, Jul 05 2014

PROG

(Haskell)

a060979 n = a060979_list !! (n-1)

a060979_list = filter (\x -> let digs = map (read . return) $ show x in

evens digs /= odds digs) [11, 22 ..]

where evens [] = 0; evens [x] = x; evens (x:_:xs) = x + evens xs

odds [] = 0; odds [x] = 0; odds (_:x:xs) = x + odds xs

-- Reinhard Zumkeller, Jul 05 2014

CROSSREFS

Cf. A135499.

STATUS

approved

editing