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A332184 a(n) = 8*(10^(2n+1)-1)/9 - 4*10^n. 2
4, 848, 88488, 8884888, 888848888, 88888488888, 8888884888888, 888888848888888, 88888888488888888, 8888888884888888888, 888888888848888888888, 88888888888488888888888, 8888888888884888888888888, 888888888888848888888888888, 88888888888888488888888888888, 8888888888888884888888888888888 (list; graph; refs; listen; history; text; internal format)
OFFSET
0,1
LINKS
FORMULA
a(n) = 8*A138148(n) + 4*10^n = A002282(2n+1)- 4*10^n = 4*A332121(n).
G.f.: (4 + 404*x - 1200*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
A332184 := n -> 8*(10^(2*n+1)-1)/9-4*10^n;
MATHEMATICA
Array[8 (10^(2 # + 1)-1)/9- 4*10^# &, 15, 0]
PROG
(PARI) apply( {A332184(n)=10^(n*2+1)\9*8-4*10^n}, [0..15])
(Python) def A332184(n): return 10**(n*2+1)//9*8-4*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. A332180 .. A332189 (variants with different middle digit 0, ..., 9).
Sequence in context: A072725 A349067 A176186 * A221232 A272167 A255269
KEYWORD
nonn,base,easy
AUTHOR
M. F. Hasler, Feb 08 2020
STATUS
approved

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Last modified February 29 06:26 EST 2024. Contains 370414 sequences. (Running on oeis4.)