A164898 First differences of numbers having only odd digits in their decimal representation.

2, 2, 2, 2, 2, 2, 2, 2, 2, 12, 2, 2, 2, 2, 12, 2, 2, 2, 2, 12, 2, 2, 2, 2, 12, 2, 2, 2, 2, 12, 2, 2, 2, 2, 12, 2, 2, 2, 2, 12, 2, 2, 2, 2, 12, 2, 2, 2, 2, 12, 2, 2, 2, 2, 112, 2, 2, 2, 2, 12, 2, 2, 2, 2, 12, 2, 2, 2, 2, 12, 2, 2, 2, 2, 12, 2, 2, 2, 2, 112, 2, 2, 2, 2, 12, 2, 2, 2, 2, 12, 2, 2, 2, 2, 12

Offset: 1

Author

Reinhard Zumkeller, Aug 30 2009

Keywords

• nonn
• base

Comments

a(n) = A014261(n+1) - A014261(n);

all terms are of the form (10^k + 8)/9, see A047855;

a(n) > 2 iff A014261(n) mod 10 = 9.

Links

• Robert Israel, Table of n, a(n) for n = 1..10000

Crossrefs

Cf. A014261.

Programs

Maple

R[1]:= [1,3,5,7,9]:
for d from 2 to 3 do
  R[d]:= map(t -> seq(10*t+i,i=[1,3,5,7,9]),R[d-1])
od:
B:= map(op,[seq(R[d],d=1..3)]):
B[2..-1]-B[1..-2]; # Robert Israel, Jan 24 2022

Mathematica

Differences[Select[Range[1000],Count[IntegerDigits[#],?EvenQ]==0&]] (* _Harvey P. Dale, Jan 03 2019 *)