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A178664
2^n concatenated with itself.
4
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
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
KEYWORD
nonn,easy,base
AUTHOR
Vincenzo Librandi, Jul 10 2010
STATUS
approved