A138142 Nonnegative numbers with digits in descending order that differ exactly by 1.

0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 21, 32, 43, 54, 65, 76, 87, 98, 210, 321, 432, 543, 654, 765, 876, 987, 3210, 4321, 5432, 6543, 7654, 8765, 9876, 43210, 54321, 65432, 76543, 87654, 98765, 543210, 654321, 765432, 876543, 987654

Offset: 1

Author

Omar E. Pol, Mar 19 2008

Keywords

• base
• easy
• fini
• nonn

Comments

This finite sequence has 55 members. The last member is 9876543210. There are 11-k members with k digits. See A052016 for primes in this sequence. All members with 3 or more digits are straight-line numbers A135643.

Examples

			Last 10 members of this finite sequence:
a(45)=6543210
a(46)=7654321
a(47)=8765432
a(48)=9876543
a(49)=76543210
a(50)=87654321
a(51)=98765432
a(52)=876543210
a(53)=987654321
a(54)=9876543210
		

Crossrefs

Cf. A052016, A135643, A138141.

Programs

Mathematica

fQ[n_]:=Module[{id=IntegerDigits[n]}, n<10 || Union[Differences[id]]=={-1}]; Select[Range[0, 100000], fQ] (* Vladimir Joseph Stephan Orlovsky, Dec 29 2010 *)
Sort[Flatten[With[{t=Range[9,0,-1]},Table[FromDigits/@Partition[t,n,1],{n,10}]]]] (* Harvey P. Dale, Oct 31 2013 *)

Extensions

Examples corrected by Omar E. Pol, Dec 06 2008