A332184 - OEIS

A332184

a(n) = 8*(10^(2*n+1) - 1)/9 - 4*10^n.

4, 848, 88488, 8884888, 888848888, 88888488888, 8888884888888, 888888848888888, 88888888488888888, 8888888884888888888, 888888888848888888888, 88888888888488888888888, 8888888888884888888888888, 888888888888848888888888888, 88888888888888488888888888888, 8888888888888884888888888888888

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OFFSET

0,1

LINKS

Table of n, a(n) for n=0..15.

Index entries for linear recurrences with constant coefficients, signature (111,-1110,1000).

FORMULA

a(n) = 8*A138148(n) + 4*10^n = A002282(2*n+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.

From Elmo R. Oliveira, Dec 11 2025: (Start)

a(n) = 2*A332142(n).

E.g.f.: 4*exp(x)*(20*exp(99*x) - 9*exp(9*x) - 2)/9. (End)

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).

Cf. A332142.

Sequence in context: A349067 A393180 A176186 * A221232 A272167 A255269

Adjacent sequences: A332181 A332182 A332183 * A332185 A332186 A332187

KEYWORD

nonn,base,easy

AUTHOR

M. F. Hasler, Feb 08 2020

STATUS

approved