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Concatenate powers of 2.
2

%I #32 Apr 06 2024 07:53:11

%S 1,12,124,1248,124816,12481632,1248163264,1248163264128,

%T 1248163264128256,1248163264128256512,12481632641282565121024,

%U 124816326412825651210242048,1248163264128256512102420484096,12481632641282565121024204840968192,1248163264128256512102420484096819216384

%N Concatenate powers of 2.

%D A. Murthy, Smarandache Notions Journal, Vol. 11 N. 1-2-3 Spring 2000. [_Felice Russo_, Nov 15 1999]

%H Vincenzo Librandi, <a href="/A045507/b045507.txt">Table of n, a(n) for n = 0..80</a>

%e a(2) = 124 because it is the concatenation of 2^0, 2^1 and 2^2.

%t Join[{1}, FromDigits/@Flatten/@IntegerDigits/@Flatten/@Rest[FoldList[List, {1}, 2^Range[25]]]] (* _Vincenzo Librandi_, Aug 10 2017 *)

%o (Magma) [Seqint(Reverse(&cat[Reverse(Intseq(2^k)): k in [0..n]])): n in [0..17]]; // _Vincenzo Librandi_, Aug 10 2017

%Y Cf. A000079, A007908.

%K nonn,base

%O 0,2

%A _Jeff Burch_