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Concatenate n-th composite integer with n.
2

%I #13 Sep 18 2014 09:39:47

%S 41,62,83,94,105,126,147,158,169,1810,2011,2112,2213,2414,2515,2616,

%T 2717,2818,3019,3220,3321,3422,3523,3624,3825,3926,4027,4228,4429,

%U 4530,4631,4832,4933,5034,5135,5236,5437,5538,5639,5740

%N Concatenate n-th composite integer with n.

%H Jens Kruse Andersen, <a href="/A245317/b245317.txt">Table of n, a(n) for n = 1..10000</a>

%e a(8)=158 since 15 is the 8th composite integer.

%t w=Select[Range[2,57],!PrimeQ[#]&];Table[FromDigits[Flatten[{IntegerDigits[w[[n]]],IntegerDigits[n]}]],{n,1,40}]

%Y Cf. A002808, A245315, A245316, A246808.

%K nonn,base

%O 1,1

%A _Jahangeer Kholdi_, Sep 15 2014