login
This site is supported by donations to The OEIS Foundation.

 

Logo

"Email this user" was broken Aug 14 to 9am Aug 16. If you sent someone a message in this period, please send it again.

Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A020744 Pisot sequences P(8,10), T(8,10). 1
8, 10, 12, 14, 16, 18, 20, 22, 24, 26, 28, 30, 32, 34, 36, 38, 40, 42, 44, 46, 48, 50, 52, 54, 56, 58, 60, 62, 64, 66, 68, 70, 72, 74, 76, 78, 80, 82, 84, 86, 88, 90, 92, 94, 96, 98, 100, 102, 104, 106, 108, 110, 112, 114, 116, 118, 120, 122, 124, 126, 128, 130, 132, 134, 136, 138 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,1

COMMENTS

Conjecturally, even sums of four primes. [Charles R Greathouse IV, Feb 16 2012]

LINKS

Colin Barker, Table of n, a(n) for n = 0..1000

Tanya Khovanova, Recursive Sequences

Index entries for linear recurrences with constant coefficients, signature (2,-1).

FORMULA

a(n) = 2n+8. a(n) = 2a(n-1) - a(n-2).

MATHEMATICA

LinearRecurrence[{2, -1}, {8, 10}, 70] (* Harvey P. Dale, Jul 19 2015 *)

P[x_, y_, z_] := Block[{a}, a[0] = x; a[1] = y; a[n_] := a[n] = Ceiling[a[n - 1]^2/a[n - 2] - 1/2]; Table[a[n], {n, 0, z}]]; P[8, 10, 65] (* or *)

T[x_, y_, z_] := Block[{a}, a[0] = x; a[1] = y; a[n_] := a[n] = Floor[a[n - 1]^2/a[n - 2]]; Table[a[n], {n, 0, z}]]; T[8, 10, 65] (* Michael De Vlieger, Aug 08 2016 *)

PROG

(PARI) a(n)=2*n+8 \\ Charles R Greathouse IV, Feb 16 2012

(PARI) pisotP(nmax, a1, a2) = {

  a=vector(nmax); a[1]=a1; a[2]=a2;

  for(n=3, nmax, a[n] = ceil(a[n-1]^2/a[n-2]-1/2));

  a

}

pisotP(50, 8, 10) \\ Colin Barker, Aug 08 2016

CROSSREFS

Subsequence of A005843, A020739. See A008776 for definitions of Pisot sequences.

Sequence in context: A033872 A080752 A262159 * A008557 A161425 A096171

Adjacent sequences:  A020741 A020742 A020743 * A020745 A020746 A020747

KEYWORD

nonn,easy

AUTHOR

David W. Wilson

STATUS

approved

Lookup | Welcome | Wiki | Register | Music | Plot 2 | Demos | Index | Browse | More | WebCam
Contribute new seq. or comment | Format | Style Sheet | Transforms | Superseeker | Recent | More pages
The OEIS Community | Maintained by The OEIS Foundation Inc.

License Agreements, Terms of Use, Privacy Policy .

Last modified August 18 08:18 EDT 2017. Contains 290685 sequences.