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.

A328356 a(n) is the sum of all positive integers whose decimal expansion is up to n digits and does not contain the 0 digit.

Original entry on oeis.org

0, 45, 4500, 409095, 36855450, 3317322645, 298562027400, 26870609370195, 2418355085455350, 217651959870221745, 19588676407933119300, 1762980876890499197295, 158668278921733593899250, 14280145102970321446216845, 1285213059267457612117075200
Offset: 0

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Author

Pierre-Alain Sallard, Dec 10 2019

Keywords

Examples

			For n=2, the sum of all integers from 1 to 99 except those containing a zero (i.e., except multiples of 10: 10, 20, ..., 90) is equal to a(2) = 4500.
For n=3, the sum of all integers from 1 to 999 except those containing a zero is equal to a(3) = 409095.
		

Crossrefs

Programs

  • PARI
    concat(0, Vec(45*x / ((1 - x)*(1 - 9*x)*(1 - 90*x)) + O(x^15))) \\ Colin Barker, Dec 10 2019
  • Python
    [(80*90**n-89*9**n+9)*5//712 for n in range(20)]
    

Formula

a(n) = (80*90^n - 89*9^n + 9) * 5 / 712.
a(n) = 91*a(n-1) - 90*a(n-2) + 45*9^(n-1) for n > 1.
G.f.: 45*x / ((1 - x)*(1 - 9*x)*(1 - 90*x)). - Colin Barker, Dec 10 2019