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.

Showing 1-2 of 2 results.

A362555 Number of distinct n-digit suffixes generated by iteratively multiplying an integer by 6, where the initial integer is 1.

Original entry on oeis.org

2, 7, 28, 129, 630, 3131, 15632, 78133, 390634, 1953135, 9765636, 48828137, 244140638, 1220703139, 6103515640, 30517578141, 152587890642, 762939453143, 3814697265644, 19073486328145, 95367431640646, 476837158203147, 2384185791015648, 11920928955078149, 59604644775390650
Offset: 1

Views

Author

Gil Moses, Apr 24 2023

Keywords

Examples

			For n = 2, we begin with 1, iteratively multiply by 6 and count the terms before the last 2 digits begin to repeat. We obtain 1, 6, 36, 216, 1296, 7776, 46656, ... . The next term is 279936, which repeats the last 2 digits 36. Thus, the number of distinct terms is a(2) = 7.
		

Crossrefs

Cf. A362468 (with 4 as the multiplier).

Programs

Formula

a(n) = 5^(n-1) + n.
From Stefano Spezia, Apr 27 2023: (Start)
O.g.f.: (1 - 5*x + 4*x^2 - 4*x^3)/((1 - x)^2*(1 - 5*x)).
E.g.f.: (4 + exp(5*x) + 5*exp(x)*x)/4. (End)

A221907 a(n) = 5^n + 5*n.

Original entry on oeis.org

1, 10, 35, 140, 645, 3150, 15655, 78160, 390665, 1953170, 9765675, 48828180, 244140685, 1220703190, 6103515695, 30517578200, 152587890705, 762939453210, 3814697265715, 19073486328220, 95367431640725, 476837158203230, 2384185791015735, 11920928955078240, 59604644775390745
Offset: 0

Views

Author

Vincenzo Librandi, Mar 02 2013

Keywords

Crossrefs

Programs

  • Magma
    [5^n + 5*n: n in [0..30]];
    
  • Magma
    I:=[1, 10, 35]; [n le 3 select I[n] else 7*Self(n-1)-11*Self(n-2)+5*Self(n-3): n in [1..30]];
    
  • Mathematica
    Table[(5^n + 5 n), {n, 0, 30}] (* or *) CoefficientList[Series[(1 + 3 x - 24 x^2)/((1 - x)^2 (1 - 5 x)), {x, 0, 30}], x]
    LinearRecurrence[{7,-11,5},{1,10,35},30] (* Harvey P. Dale, Jul 23 2013 *)
  • PARI
    a(n)=5^n+5*n \\ Charles R Greathouse IV, Apr 18 2013

Formula

G.f.: (1+3*x-24*x^2)/((1-x)^2*(1-5*x)).
a(n) = 7*a(n-1) - 11*a(n-2) + 5*a(n-3).
a(n) = A176916(n) - 1.
a(n) = 5*A362555(n) for n > 0. - Hugo Pfoertner, Mar 01 2024
E.g.f.: exp(x)*(exp(4*x) + 5*x). - Elmo R. Oliveira, Sep 10 2024
Showing 1-2 of 2 results.