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 A048992 Hannah Rollman's numbers: the numbers excluded from A048991. 13
 12, 23, 31, 34, 41, 42, 45, 51, 52, 53, 56, 61, 62, 63, 64, 67, 71, 72, 73, 74, 75, 78, 81, 82, 83, 84, 85, 86, 89, 91, 92, 93, 94, 95, 96, 97, 98, 101, 111, 113, 121, 122, 123, 131, 141, 151, 161, 171, 181, 191, 192, 201, 202, 210, 211, 212, 213, 214, 215, 216, 217 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,1 COMMENTS A105390(n) = number of terms <= n; for n < 740: A105390(n) < n/2. - Reinhard Zumkeller, Apr 04 2005 A116700 is a similar sequence. Note that 21 is missing from the current sequence, because we deleted 12 in computing A048991 and now 21 is no longer "earlier in the sequence". On the other hand 21 is present in A116700. - N. J. A. Sloane, Aug 05 2007 Otherwise said: Numbers which occur in the concatenation of all smaller numbers not listed in this sequence. - M. F. Hasler, Dec 29 2012 LINKS T. D. Noe, Table of n, a(n) for n=1..10000 Nick Hobson, Python program for this sequence MATHEMATICA a[0] = 1; s = "1"; a[n_] := a[n] = For[k = a[n-1] + 1, True, k++, If[StringFreeQ[s, t = ToString[k]], s = s <> t, Return[k]]]; Table[a[n], {n, 1, 100}] (* Jean-François Alcover, Nov 25 2013 *) PROG (Python) see Hobson link (Haskell) import Data.List (isInfixOf) a048992 n = a048992_list !! (n-1) a048992_list = g [1..] [] where    g (x:xs) ys | xs' `isInfixOf` ys = x : g xs ys                | otherwise          = g xs (xs' ++ ys)                where xs' = reverse \$ show x -- Reinhard Zumkeller, Dec 05 2011 CROSSREFS Sequence in context: A246342 A101104 A114455 * A088783 A029756 A104340 Adjacent sequences:  A048989 A048990 A048991 * A048993 A048994 A048995 KEYWORD nonn,nice,base,easy,look AUTHOR Bernardo Recamán (ignotus(AT)hotmail.com) EXTENSIONS Edited by Patrick De Geest, Jun 02 2003 STATUS approved

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Last modified October 15 13:38 EDT 2019. Contains 328030 sequences. (Running on oeis4.)