A291663 Numbers beginning with a vowel in Danish.

1, 8, 11, 18, 21, 28, 31, 38, 41, 48, 51, 58, 61, 68, 71, 78, 81, 88, 91, 98, 100, 101, 102, 103, 104, 105, 106, 107, 108, 109, 110, 111, 112, 113, 114, 115, 116, 117, 118, 119, 120, 121, 122, 123, 124, 125, 126, 127, 128, 129, 130, 131, 132, 133, 134, 135, 136, 137, 138, 139, 140, 141, 142, 143, 144, 145, 146, 147, 148, 149

Offset: 1

Author

Halfdan Skjerning, Aug 29 2017

Keywords

• nonn
• easy
• word

Comments

The sequence of words is: en, otte, elleve, atten, enogtyve, otteogtyve, enogtredive, otteogtredive, enogfyrre, otteogfyrre, enoghalvtreds, otteoghalvtreds, enogtreds, otteogtreds, enoghalvfjerds, ...

Links

• Halfdan Skjerning, Table of n, a(n) for n = 1..150
• Brady Haran and Tom Scott, 58 and other Confusing Numbers, Numberphile video (2015)
• Wikipedia, List of numbers in various languages

Crossrefs

Cf. A000861, A079741, A098060, A247751, A291621.

Programs

Mathematica

Select[Range@ 149, With[{d = IntegerDigits@ #}, MemberQ[{1, 8}, If[Length@ d == 2, First@ Reverse@ d, First@ d]]] &] (* Michael De Vlieger, Aug 30 2017 *)

Formula

All numbers beginning with '1' or '8', except for two-digit numbers that do not end in '1' or '8'.