A332185 a(n) = 8*(10^(2n+1)-1)/9 - 3*10^n.

5, 858, 88588, 8885888, 888858888, 88888588888, 8888885888888, 888888858888888, 88888888588888888, 8888888885888888888, 888888888858888888888, 88888888888588888888888, 8888888888885888888888888, 888888888888858888888888888, 88888888888888588888888888888, 8888888888888885888888888888888

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) + 5*10^n = A002282(2n+1) - 3*10^n.

G.f.: (5 + 303*x - 1100*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

A332185 := n -> 8*(10^(2*n+1)-1)/9-3*10^n;

Mathematica

Array[8 (10^(2 # + 1)-1)/9 - 3*10^# &, 15, 0]

Prog

(PARI) apply( {A332185(n)=10^(n*2+1)\9*8-3*10^n}, [0..15])
(Python) def A332185(n): return 10**(n*2+1)//9*8-3*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), A002113 (palindromes).

Cf. A332180 .. A332189 (variants with different middle digit 0, ..., 9).

Cf. A332115 .. A332195 (variants with different "wing" digit 1, ..., 9).

Sequence in context: A060713 A198402 A214450 * A085706 A190350 A135084

Adjacent sequences: A332182 A332183 A332184 * A332186 A332187 A332188

Keyword

nonn,base,easy

Author

M. F. Hasler, Feb 08 2020

Status

approved