A206529 7^n concatenated with itself.

11, 77, 4949, 343343, 24012401, 1680716807, 117649117649, 823543823543, 57648015764801, 4035360740353607, 282475249282475249, 19773267431977326743, 1384128720113841287201, 9688901040796889010407, 678223072849678223072849

Offset

0,1

Links

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

Formula

a(n) = A020338(7^n).

Example

a(1)=77 because 7^1 concatenated with 7^1 is 77.

Mathematica

Table[FromDigits[Join[IntegerDigits[7^n], IntegerDigits[7^n]]], {n, 0, 20}]
#*10^IntegerLength[#]+#&/@(7^Range[0, 20]) (* Harvey P. Dale, Jul 19 2022 *)

Prog

(Magma) [Seqint(Intseq(7^n) cat Intseq(7^n)): n in [0..20]];

Crossrefs

Cf. A000420, A000351, A178664, A206527, A206528.

Sequence in context: A322877 A377918 A226708 * A118936 A041224 A030054

Adjacent sequences: A206526 A206527 A206528 * A206530 A206531 A206532

Keyword

nonn,base,easy

Author

Vincenzo Librandi, Mar 18 2012

Status

approved