A082927 Numbers in which at least one pair of adjacent digits differ by 1.

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

Offset: 1

Author

Anonymous, Apr 15 2003

Keywords

• base
• easy
• nonn

Examples

			1998 is a term because 8 and 9 differ by 1.
		

Programs

Mathematica

Select[Range[250],MemberQ[Abs[Differences[IntegerDigits[#]]],1]&] (* Harvey P. Dale, Apr 07 2018 *)

PARI

isok(n) = (d = digits(n)) && (sum(i=1, #d-1, abs(d[i] - d[i+1])==1) >= 1); \\ Michel Marcus, Mar 11 2014

Formula

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

Extensions

120 added by Zak Seidov, Mar 11 2014

Name clarified by Jon E. Schoenfield, Oct 29 2022