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A082927
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Numbers in which at least one pair of adjacent digits differ by 1.
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4
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10, 12, 21, 23, 32, 34, 43, 45, 54, 56, 65, 67, 76, 78, 87, 89, 98, 100, 101, 102, 103, 104, 105, 106, 107, 108, 109, 110, 112, 120, 121, 122, 123, 124, 125, 126, 127, 128, 129, 132, 134, 143, 145, 154, 156, 165, 167, 176, 178, 187, 189, 198, 201, 210, 211, 212, 213
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OFFSET
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1,1
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LINKS
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FORMULA
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a(n) = n + O(x^0.915), where the exponent is the log(k)/log(10) with k the largest root of x^5 - 9x^4 + 4x^3 + 21x^2 - 9x - 5. - Charles R Greathouse IV, Mar 11 2014
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EXAMPLE
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1998 is a term because 8 and 9 differ by 1.
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MATHEMATICA
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Select[Range[250], MemberQ[Abs[Differences[IntegerDigits[#]]], 1]&] (* Harvey P. Dale, Apr 07 2018 *)
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PROG
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(PARI) isok(n) = (d = digits(n)) && (sum(i=1, #d-1, abs(d[i] - d[i+1])==1) >= 1); \\ Michel Marcus, Mar 11 2014
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CROSSREFS
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KEYWORD
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base,easy,nonn
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AUTHOR
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Anonymous, Apr 15 2003
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EXTENSIONS
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STATUS
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approved
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