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A061470
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First (leftmost) digit - second digit + third digit - fourth digit .... = 1.
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28
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1, 10, 21, 32, 43, 54, 65, 76, 87, 98, 100, 111, 122, 133, 144, 155, 166, 177, 188, 199, 210, 221, 232, 243, 254, 265, 276, 287, 298, 320, 331, 342, 353, 364, 375, 386, 397, 430, 441, 452, 463, 474, 485, 496, 540, 551, 562, 573, 584, 595, 650, 661, 672, 683
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OFFSET
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1,2
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LINKS
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FORMULA
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EXAMPLE
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221 is in the sequence since 2-2+1 = 1.
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MATHEMATICA
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d[n_]:=IntegerDigits[n]; a[n_]:=Differences[Reverse[Total/@{Take[d[n], {1, -1, 2}], Take[d[n], {2, -1, 2}]}]]; Select[Range[690], a[#]=={1} &] (* Jayanta Basu, May 18 2013 *)
Select[Range[1000], Total[Times@@@Partition[Riffle[IntegerDigits[#], {1, -1}, {2, -1, 2}], 2]]==1&] (* Harvey P. Dale, May 24 2021 *)
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PROG
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(Haskell)
a061470 n = a061470_list !! (n-1)
a061470_list = filter ((== 1) . a225693) [0..]
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CROSSREFS
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KEYWORD
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nonn,base,easy
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AUTHOR
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EXTENSIONS
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More terms from Robert G. Wilson v, May 10 2001 and from Larry Reeves (larryr(AT)acm.org), May 14 2001
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STATUS
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approved
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