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A102492
Numbers in base-20 representation that cannot be written with decimal digits.
5
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
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
KEYWORD
nonn,base,changed
AUTHOR
Reinhard Zumkeller, Jan 12 2005
STATUS
approved