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Concatenation of n and n + 9 or {n,n+9}.
2

%I #18 Feb 17 2024 10:29:21

%S 110,211,312,413,514,615,716,817,918,1019,1120,1221,1322,1423,1524,

%T 1625,1726,1827,1928,2029,2130,2231,2332,2433,2534,2635,2736,2837,

%U 2938,3039,3140,3241,3342,3443,3544,3645,3746,3847,3948,4049,4150,4251,4352,4453,4554,4655

%N Concatenation of n and n + 9 or {n,n+9}.

%H Tanya Khovanova, <a href="http://www.tanyakhovanova.com/RecursiveSequences/NonRecursions.html">Non Recursions</a>

%t a[n_]:=n*10^Floor[Log10[n+9]+1]+n+9; Array[a,46] (* _Stefano Spezia_, Sep 04 2023 *)

%Y Cf. A001704, A020338.

%K nonn,base,easy

%O 1,1

%A _Patrick De Geest_, May 15 1998

%E a(42)-a(46) from _Stefano Spezia_, Sep 04 2023