cp's OEIS Frontend

A125887 a(1) = 1, a(n) = smallest positive number b not among a(1)..a(n-1) and not a multiple of 10 such that the first digit of b = the last digit of a(n-1).

%I A125887 #8 Jan 27 2014 16:22:23
%S A125887 1,11,12,21,13,31,14,41,15,51,16,61,17,71,18,81,19,91,101,102,22,23,
%T A125887 32,24,42,25,52,26,62,27,72,28,82,29,92,201,103,33,34,43,35,53,36,63,
%U A125887 37,73,38,83,39,93,301,104,44,45,54,46,64,47,74,48,84,49,94,401,105,55,56,65
%N A125887 a(1) = 1, a(n) = smallest positive number b not among a(1)..a(n-1) and not a multiple of 10 such that the first digit of b = the last digit of a(n-1).
%C A125887 A dyslexic person might have trouble distinguishing this sequence from A125886!
%H A125887 Reinhard Zumkeller, <a href="/A125887/b125887.txt">Table of n, a(n) for n = 1..10000</a>
%o A125887 (Haskell)
%o A125887 a125887 n = a125887_list !! (n-1)
%o A125887 a125887_list = 1 : f '1' (filter ((> 0) . (`mod` 10)) [11..]) where
%o A125887    f d zs = y : f (last $ show y) (xs ++ ys) where
%o A125887        (xs, y:ys) = span ((/= d) . head . show) zs
%o A125887 -- _Reinhard Zumkeller_, Jul 06 2011
%Y A125887 Cf. A125886.
%Y A125887 Cf. A000030, A010879.
%K A125887 base,nonn,look
%O A125887 1,2
%A A125887 _Zak Seidov_, Dec 13 2006