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A332182
a(n) = 8*(10^(2n+1)-1)/9 - 6*10^n.
2
2, 828, 88288, 8882888, 888828888, 88888288888, 8888882888888, 888888828888888, 88888888288888888, 8888888882888888888, 888888888828888888888, 88888888888288888888888, 8888888888882888888888888, 888888888888828888888888888, 88888888888888288888888888888, 8888888888888882888888888888888
OFFSET
0,1
FORMULA
a(n) = 8*A138148(n) + 2*10^n = A002282(2n+1)- 6*10^n.
G.f.: (2 + 606*x - 1400*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.
MAPLE
A332182 := n -> 8*(10^(2*n+1)-1)/9-6*10^n;
MATHEMATICA
Array[8 (10^(2 # + 1)-1)/9 - 6*10^# &, 15, 0]
PROG
(PARI) apply( {A332182(n)=10^(n*2+1)\9*8-6*10^n}, [0..15])
(Python) def A332182(n): return 10**(n*2+1)//9*8-6*10**n
CROSSREFS
Cf. A002275 (repunits R_n = (10^n-1)/9), A002282 (8*R_n), A011557 (10^n).
Cf. A138148 (cyclops numbers with binary digits only).
Cf. A332112 .. A332192 (variants with different repeated digit 1, ..., 9).
Cf. A332180 .. A332189 (variants with different middle digit 0, ..., 9).
Sequence in context: A281195 A109555 A214898 * A230396 A028485 A034227
KEYWORD
nonn,base,easy
AUTHOR
M. F. Hasler, Feb 08 2020
STATUS
approved