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A061870
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Numbers with property that |first digit - second digit + third digit - fourth digit ...| = 1.
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27
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1, 10, 12, 21, 23, 32, 34, 43, 45, 54, 56, 65, 67, 76, 78, 87, 89, 98, 100, 111, 120, 122, 131, 133, 142, 144, 153, 155, 164, 166, 175, 177, 186, 188, 197, 199, 210, 221, 230, 232, 241, 243, 252, 254, 263, 265, 274, 276, 285, 287, 296, 298, 320, 331, 340, 342
(list; graph; refs; listen; history; internal format)
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OFFSET
| 1,2
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COMMENTS
| Multiples of 11 plus or minus 1 if 11k+1 is a perfect square..(0,9,13,40,48,93,105...) then a(n) is the square root of 11k+1 [From Gary Detlefs (gdetlefs(AT)aol.com), Feb 22 2010]
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EXAMPLE
| 120 is in the sequence since |1-2+0| = 1.
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MATHEMATICA
| fQ[n_] := Abs[Plus @@ (((-1)^Range[Floor[Log[10, n] + 1]])*IntegerDigits@n)] == 1; Select[ Range@342, fQ@# &]
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CROSSREFS
| Cf. A008593, A060978-A060980, A060982, A061470-A061479, A061870-A061882.
Sequence in context: A082927 A108965 A175885 * A120001 A108703 A098785
Adjacent sequences: A061867 A061868 A061869 * A061871 A061872 A061873
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KEYWORD
| nonn,base,easy
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AUTHOR
| Robert G. Wilson v (rgwv(AT)rgwv.com), May 10 2001
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