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A156641
a(n) = 13*(100^(n+1) - 1)/99.
2
13, 1313, 131313, 13131313, 1313131313, 131313131313, 13131313131313, 1313131313131313, 131313131313131313, 13131313131313131313, 1313131313131313131313, 131313131313131313131313
OFFSET
0,1
FORMULA
G.f.: 13*x / ( (1-100*x)*(1-x) ).
a(n) = 13*A094028(n-1).
E.g.f.: (13/99)*(-exp(x) + 100*exp(100*x)). - G. C. Greubel, Feb 28 2021
EXAMPLE
For n=0, a(0)=13; n=1, a(1)=1313; n=2, a(2)=131313; n=3, a(3)=13131313.
MAPLE
A156641:= n-> (13/99)*(10^(2*n+2) -1); seq(A156641(n), n=0..15); # G. C. Greubel, Feb 28 2021
MATHEMATICA
Table[FromDigits[PadLeft[{1, 3}, 2n, {1, 3}]], {n, 15}] (* Harvey P. Dale, Jul 23 2011 *)
PROG
(Magma) [13*(100^(n+1)-1)/99: n in [0..15]];
(Sage) [(13/99)*(10^(2*n+2) -1) for n in (0..15)] # G. C. Greubel, Feb 28 2021
(PARI) a(n) = 100^(n+1)\99*13; \\ Kevin Ryde, Mar 05 2022
CROSSREFS
Sequence in context: A220619 A178560 A091781 * A300592 A221690 A197630
KEYWORD
nonn,easy
AUTHOR
Vincenzo Librandi, Feb 15 2009
EXTENSIONS
Offset changed from 1 to 0
STATUS
approved