cp's OEIS Frontend

This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.

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

Original entry on oeis.org

5, 858, 88588, 8885888, 888858888, 88888588888, 8888885888888, 888888858888888, 88888888588888888, 8888888885888888888, 888888888858888888888, 88888888888588888888888, 8888888888885888888888888, 888888888888858888888888888, 88888888888888588888888888888, 8888888888888885888888888888888
Offset: 0

Views

Author

M. F. Hasler, Feb 08 2020

Keywords

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).

Programs

  • 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]
  • 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

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.