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
KEYWORD
nonn,base,easy
AUTHOR
Vincenzo Librandi, Mar 18 2012
STATUS
approved