A284922 Numbers with digits 2 and 8 only.

2, 8, 22, 28, 82, 88, 222, 228, 282, 288, 822, 828, 882, 888, 2222, 2228, 2282, 2288, 2822, 2828, 2882, 2888, 8222, 8228, 8282, 8288, 8822, 8828, 8882, 8888, 22222, 22228, 22282, 22288, 22822, 22828, 22882, 22888, 28222, 28228, 28282, 28288, 28822, 28828

Offset: 1

Author

Jaroslav Krizek, Apr 05 2017

Keywords

• nonn
• base

Comments

All terms are even.

Crossrefs

Cf. Numbers with digits 2 and k only for k = 0 - 1 and 3 - 9: A169965 (k = 0), A007931 (k = 1), A032810 (k = 3), A284920 (k = 4), A072961 (k = 5), A284632 (k = 6), A284921 (k = 7), this sequence (k = 8), A284923 (k = 9).

Programs

Magma

[n: n in [1..100000] | Set(IntegerToSequence(n, 10)) subset {2, 8}]

Mathematica

Flatten@ Array[FromDigits /@ Tuples[{2, 8}, #] &, 5] (* Michael De Vlieger, Apr 06 2017 *)

Formula

a(n) = 2 * A032822(n).