A138142 -id:A138142 - cp's OEIS frontend

A138141 Numbers with digits in ascending order that differ exactly by 1.

1, 2, 3, 4, 5, 6, 7, 8, 9, 12, 23, 34, 45, 56, 67, 78, 89, 123, 234, 345, 456, 567, 678, 789, 1234, 2345, 3456, 4567, 5678, 6789, 12345, 23456, 34567, 45678, 56789, 123456, 234567, 345678, 456789, 1234567, 2345678, 3456789, 12345678, 23456789, 123456789

Offset: 1

Omar E. Pol, Mar 19 2008

This finite sequence has 45 members. The last member is 123456789. There are 10-k members with k digits. See A052017 for primes in this sequence. All members with 3 or more digits are straight-line numbers A135643.

Cf. A052017, A059043, A135643, A138142.

Table[FromDigits/@Partition[Range[9],n,1],{n,9}]//Flatten (* Harvey P. Dale, Mar 19 2017 *)

a(n) = floor(((9*t^2 - 189*t + 18*n + 182) * (10^t - 1) - 18*t) / 162), where t = floor((21 - sqrt(369 - 8*n)) / 2). - Christopher J. Thomas, Feb 14 2024

A052016 Primes with digits in descending order that differ exactly by 1.

Original entry on oeis.org

2, 3, 5, 7, 43, 76543

Offset: 1

Patrick De Geest, Nov 15 1999

Primes in A138142. - Omar E. Pol, Dec 07 2008

Cf. A052017, A048398, A006055, A138142.

fQ[n_]:=Module[{id=IntegerDigits[n],}, n < 10 || Union[Differences[id]] == {-1}]; Select[Prime[Range[10000]], fQ] (* Vladimir Joseph Stephan Orlovsky, Dec 29 2010 *)

A178356 Fibonacci numbers whose successive digits decrease by 1.

Original entry on oeis.org

0, 1, 2, 3, 5, 8, 21, 987

Offset: 1

Felix Tubiana, May 25 2010

Only need to consider the Fibonacci numbers less than 9876543210.

Cf. A000045, A138142, A178355.

Join[{0,1,2,3,5,8},Select[Fibonacci[Range[250]],Union[Differences[ IntegerDigits[#]]]=={-1}&]] (* Harvey P. Dale, Sep 14 2011 *)

n=0;while((f=fibonacci(n))<=9876543210,if(is(f),print1(f", "));n++) \\ Charles R Greathouse IV, Sep 14 2011

{ A000045 } intersect { A138142 }. - Alois P. Heinz, Jul 05 2022

Definition clarified by Harvey P. Dale, Sep 14 2011

cp's OEIS Frontend

A138141 Numbers with digits in ascending order that differ exactly by 1.

Views

Author

Keywords

Comments

Crossrefs

Programs

Mathematica

Formula

A052016 Primes with digits in descending order that differ exactly by 1.

Views

Author

Keywords

Comments

Crossrefs

Programs

Mathematica

A178356 Fibonacci numbers whose successive digits decrease by 1.

Views

Author

Keywords

Comments

Crossrefs

Programs

Mathematica

PARI

Formula

Extensions