A284632 Numbers n with digits 2 and 6 only.

2, 6, 22, 26, 62, 66, 222, 226, 262, 266, 622, 626, 662, 666, 2222, 2226, 2262, 2266, 2622, 2626, 2662, 2666, 6222, 6226, 6262, 6266, 6622, 6626, 6662, 6666, 22222, 22226, 22262, 22266, 22622, 22626, 22662, 22666, 26222, 26226, 26262, 26266, 26622, 26626

Offset

1,1

Comments

All terms after 2 are composite.

Links

Table of n, a(n) for n=1..44.

Formula

a(n) = 2 * A032917(n).

Mathematica

Table[Map[FromDigits, Tuples[{2, 6}, {k}]], {k, 5}] // Flatten (* Michael De Vlieger, Mar 30 2017 *)

Prog

(Magma) [n: n in [1..100000] | Set(IntegerToSequence(n, 10)) subset {2, 6}]

Crossrefs

Cf. A032917.

Numbers n with digits 6 and k only for k = 0..5 and 7..9: A204093 (k = 0), A284293 (k = 1), this sequence (k = 2), A284633 (k = 3), A284634 (k = 4), A256291 (k = 5), A256292 (k = 7), A284635 (k = 8), A284636 (k = 9).

Sequence in context: A216719 A085286 A062085 * A350553 A325020 A335131

Adjacent sequences: A284629 A284630 A284631 * A284633 A284634 A284635

Keyword

nonn,base

Author

Jaroslav Krizek, Mar 30 2017

Status

approved