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A060979
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|First digit - second digit + third digit - fourth digit ...| = 11.
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3
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209, 308, 319, 407, 418, 429, 506, 517, 528, 539, 605, 616, 627, 638, 649, 704, 715, 726, 737, 748, 759, 803, 814, 825, 836, 847, 858, 869, 902, 913, 924, 935, 946, 957, 968, 979, 1309, 1408, 1419, 1507, 1518, 1529, 1606, 1617, 1628, 1639, 1705, 1716
(list;
graph;
refs;
listen;
history;
text;
internal format)
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OFFSET
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1,1
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COMMENTS
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Note that all terms are divisible by eleven.
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LINKS
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MAPLE
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filter:= proc(n) local L, i;
L:= convert(n, base, 10);
abs(add(L[i]*(-1)^i, i=1..nops(L))) = 11
end proc:
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MATHEMATICA
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Do[ a = IntegerDigits[ n ]; l = Length[ a ]; e = o = {}; Do[ o = Append[ o, a[ [ 2k - 1 ] ] ], {k, 1, l/2 + .5} ]; Do[ e = Append[ e, a[ [ 2k ] ] ], {k, 1, l/2} ]; If[ Abs[ Apply[ Plus, o ] - Apply[ Plus, e ] ] == 11, Print[ n ] ], {n, 1, 2000} ]
d11Q[n_]:=Module[{idn=IntegerDigits[n]}, Abs[Total[Table[(-1)^(i+1) idn[[i]], {i, Length[idn]}]]]==11]; Select[Range[1800], d11Q] (* Harvey P. Dale, Aug 26 2012 *)
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PROG
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(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
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CROSSREFS
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KEYWORD
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base,nonn,easy
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AUTHOR
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EXTENSIONS
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STATUS
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approved
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