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Numbers n put into lexicographical order which are the concatenation of k and the sum of the digits of k.
4

%I #9 May 16 2019 14:26:04

%S 11,22,33,44,55,66,77,88,99,101,112,123,134,145,156,167,178,189,202,

%T 213,224,235,246,257,268,279,303,314,325,336,347,358,369,404,415,426,

%U 437,448,459,505,516,527,538,549,606,617,628,639,707,718,729,808,819,909,1001

%N Numbers n put into lexicographical order which are the concatenation of k and the sum of the digits of k.

%e 1 --> 11, 2 --> 22, 3 --> 33, ..., 9 --> 99, 10 --> 101, 11 --> 112, 12 --> 123,

%e ..., 18 --> 189, 19 --> 1910 (ouch!), 20 --> 202, 21 --> 213, ...

%t f[n_] := FromDigits[ Join[ IntegerDigits[ n], IntegerDigits[Plus @@ IntegerDigits[ n]] ]]; t = {}; Do[t = Union[AppendTo[t, f[n]]], {n, 10^6}]

%Y Cf. A062028, A064806. Equals A108773 sorted.

%K base,nonn

%O 1,1

%A _Eric Angelini_ and _Robert G. Wilson v_, Jun 15 2005

%E a(55) from _Rémy Sigrist_, May 16 2019