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

1,1

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

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 *)

Crossrefs

Cf. A014261.

Sequence in context: A252375 A339170 A257773 * A100801 A194310 A306227

Adjacent sequences: A164895 A164896 A164897 * A164899 A164900 A164901

Keyword

nonn,base

Author

Reinhard Zumkeller, Aug 30 2009

Status

approved