A332186 a(n) = 8*(10^(2n+1)-1)/9 - 2*10^n.
6, 868, 88688, 8886888, 888868888, 88888688888, 8888886888888, 888888868888888, 88888888688888888, 8888888886888888888, 888888888868888888888, 88888888888688888888888, 8888888888886888888888888, 888888888888868888888888888, 88888888888888688888888888888, 8888888888888886888888888888888
Offset: 0
Links
- Index entries for linear recurrences with constant coefficients, signature (111,-1110,1000).
Crossrefs
Programs
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Maple
A332186 := n -> 8*(10^(2*n+1)-1)/9-2*10^n;
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Mathematica
Array[8 (10^(2 # + 1)-1)/9 - 2*10^# &, 15, 0] LinearRecurrence[{111,-1110,1000},{6,868,88688},20] (*or *) Table[FromDigits[Join[PadRight[ {},n,8],PadRight[ {6},n+1,8]]],{n,0,20}] (* Harvey P. Dale, May 30 2023 *) -
PARI
apply( {A332186(n)=10^(n*2+1)\9*8-2*10^n}, [0..15]) -
Python
def A332186(n): return 10**(n*2+1)//9*8-2*10**n
Formula
G.f.: (6 + 202*x - 1000*x^2)/((1 - x)(1 - 10*x)(1 - 100*x)).
a(n) = 111*a(n-1) - 1110*a(n-2) + 1000*a(n-3) for n > 2.
E.g.f.: 2*exp(x)*(40*exp(99*x) - 9*exp(9*x) - 4)/9. - Stefano Spezia, Jul 13 2024