A206527 3^n concatenated with itself.

11, 33, 99, 2727, 8181, 243243, 729729, 21872187, 65616561, 1968319683, 5904959049, 177147177147, 531441531441, 15943231594323, 47829694782969, 1434890714348907, 4304672143046721, 129140163129140163, 387420489387420489

Offset

0,1

Links

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

Formula

a(n) = A020338(3^n). - Bruno Berselli, Mar 14 2012

Example

a(1)=33 because 3^1 concatenated with 3^1 is 33.

Mathematica

Table[FromDigits[Join[IntegerDigits[3^n], IntegerDigits[3^n]]], {n, 0, 18}] (* Bruno Berselli, Mar 14 2012 *)
Table[3^n 10^IntegerLength[3^n]+3^n, {n, 0, 20}] (* Harvey P. Dale, May 27 2019 *)

Prog

(Magma) [Seqint(Intseq(3^n) cat Intseq(3^n)): n in [0..18]]; // Bruno Berselli, Mar 14 2012

Crossrefs

Cf. A178664, A000244.

Sequence in context: A027025 A366135 A120354 * A297478 A213973 A262913

Adjacent sequences: A206524 A206525 A206526 * A206528 A206529 A206530

Keyword

nonn,base,easy

Author

Vincenzo Librandi, Mar 14 2012

Status

approved