A102492 Numbers in base-20 representation that cannot be written with decimal digits.

10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 50, 51, 52, 53, 54, 55, 56, 57, 58, 59, 70, 71, 72, 73, 74, 75, 76, 77, 78, 79, 90, 91, 92, 93, 94, 95, 96, 97, 98, 99, 110, 111, 112, 113, 114, 115, 116, 117, 118, 119, 130, 131, 132, 133

Offset

1,1

Links

Reinhard Zumkeller, Table of n, a(n) for n = 1..10000

Eric Weisstein's World of Mathematics, Vigesimal

Wikipedia, Vigesimal

Example

112 = 5*20^1 + 12*20^0 = '5C', therefore 112 is a term.

Mathematica

Select[Range[150], Max[IntegerDigits[#, 20]]>9&] (* Harvey P. Dale, Mar 27 2021 *)

Prog

(Haskell)
import Data.List (unfoldr)
a102492 n = a102492_list !! (n-1)
a102492_list = filter (any (> 9) . unfoldr
   (\x -> if x == 0 then Nothing else Just $ swap $ divMod x 20)) [0..]
-- Reinhard Zumkeller, Jun 27 2013

Crossrefs

Complement of A102491; A102488, A102490, A102494.

Sequence in context: A161561 A307560 A007959 * A169905 A076161 A318699

Adjacent sequences: A102489 A102490 A102491 * A102493 A102494 A102495

Keyword

nonn,base

Author

Reinhard Zumkeller, Jan 12 2005

Status

approved