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A332186
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a(n) = 8*(10^(2n+1)-1)/9 - 2*10^n.
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2
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6, 868, 88688, 8886888, 888868888, 88888688888, 8888886888888, 888888868888888, 88888888688888888, 8888888886888888888, 888888888868888888888, 88888888888688888888888, 8888888888886888888888888, 888888888888868888888888888, 88888888888888688888888888888, 8888888888888886888888888888888
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listen;
history;
text;
internal format)
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OFFSET
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0,1
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LINKS
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Table of n, a(n) for n=0..15.
Index entries for linear recurrences with constant coefficients, signature (111,-1110,1000).
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FORMULA
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a(n) = 8*A138148(n) + 6*10^n = A002282(2n+1) - 2*10^n = 2*A332143(n).
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.
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MAPLE
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A332186 := n -> 8*(10^(2*n+1)-1)/9-2*10^n;
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MATHEMATICA
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Array[8 (10^(2 # + 1)-1)/9 - 2*10^# &, 15, 0]
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PROG
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(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
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CROSSREFS
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Cf. A002275 (repunits R_n = (10^n-1)/9), A002282 (8*R_n), A011557 (10^n).
Cf. A138148 (cyclops numbers with binary digits), A002113 (palindromes).
Cf. A332180 .. A332189 (variants with different middle digit 0, ..., 9).
Sequence in context: A201141 A078927 A064430 * A279304 A180992 A229629
Adjacent sequences: A332183 A332184 A332185 * A332187 A332188 A332189
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KEYWORD
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nonn,base,easy
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AUTHOR
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M. F. Hasler, Feb 08 2020
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STATUS
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approved
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