A178664 2^n concatenated with itself.

11, 22, 44, 88, 1616, 3232, 6464, 128128, 256256, 512512, 10241024, 20482048, 40964096, 81928192, 1638416384, 3276832768, 6553665536, 131072131072, 262144262144, 524288524288, 10485761048576, 20971522097152, 41943044194304

Offset

0,1

Comments

a(1)=22 because 2^1 concatenated with 2^1 is 22.

Links

Vincenzo Librandi, Table of n, a(n) for n = 0..200

Formula

a(n) = A020338(2^n). - Bruno Berselli, Mar 14 2012

Mathematica

Table[FromDigits[Join[IntegerDigits[2^n], IntegerDigits[2^n]]], {n, 0, 30}] (* Vincenzo Librandi, Mar 14 2012 *)
#*10^IntegerLength[#]+#&/@(2^Range[0, 25]) (* Harvey P. Dale, Aug 29 2024 *)

Prog

(Magma) [Seqint(Intseq(2^n) cat Intseq(2^n)): n in [0..40]]; // Vincenzo Librandi, Mar 14 2012

Crossrefs

Cf. A000079.

Sequence in context: A367348 A005015 A070069 * A292926 A109687 A225361

Adjacent sequences: A178661 A178662 A178663 * A178665 A178666 A178667

Keyword

nonn,easy,base

Author

Vincenzo Librandi, Jul 10 2010

Status

approved