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Multiples of 4 that are the concatenation of 4 consecutive natural numbers.
5

%I #4 Jun 16 2023 17:34:11

%S 3456,9101112,13141516,17181920,21222324,25262728,29303132,33343536,

%T 37383940,41424344,45464748,49505152,53545556,57585960,61626364,

%U 65666768,69707172,73747576,77787980,81828384,85868788,89909192,93949596,979899100,101102103104

%N Multiples of 4 that are the concatenation of 4 consecutive natural numbers.

%C Except for the first term all the other terms are a concatenation of 4 numbers from 4k+1 to 4k+4. All the natural numbers are used except 1,2,7 and 8.

%t Select[FromDigits[Flatten[IntegerDigits[#]]]&/@Partition[Range[100],4,1],Mod[#,4]==0&] (* _Harvey P. Dale_, Jun 16 2023 *)

%Y Cf. A082243.

%K base,easy,nonn

%O 1,1

%A _Amarnath Murthy_, Apr 11 2003

%E More terms from _Harvey P. Dale_, Jun 16 2023