login
The OEIS Foundation is supported by donations from users of the OEIS and by a grant from the Simons Foundation.

 

Logo


Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A112132 Period 4: repeat [1, 3, 1, 7]. 2
1, 3, 1, 7, 1, 3, 1, 7, 1, 3, 1, 7, 1, 3, 1, 7, 1, 3, 1, 7, 1, 3, 1, 7, 1, 3, 1, 7, 1, 3, 1, 7, 1, 3, 1, 7, 1, 3, 1, 7, 1, 3, 1, 7, 1, 3, 1, 7, 1, 3, 1, 7, 1, 3, 1, 7, 1, 3, 1, 7, 1, 3, 1, 7, 1, 3, 1, 7, 1, 3, 1, 7, 1, 3, 1, 7, 1, 3, 1, 7, 1, 3, 1, 7, 1, 3, 1 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

COMMENTS

Terms of the simple continued fraction of 10/(3*sqrt(205)-35). Decimal expansion of 4390/3333. [Paolo P. Lava, Aug 05 2009]

LINKS

Table of n, a(n) for n=1..87.

Index entries for linear recurrences with constant coefficients, signature (0,0,0,1).

FORMULA

a(n) = 2*(n mod 4)-[(n+1) mod 4]+[(n+2) mod 4]. - Paolo P. Lava, Aug 29 2007

a(n) = 3+I*I^(n-1)+2*(-1)^n-I*(-I)^(n-1). - Paolo P. Lava, Jul 17 2008

a(n+1) = 3-2*sin(Pi*n/2)-2*(-1)^n. - R. J. Mathar, Oct 08 2011

Multiplicative with a(2) = 3, a(2^e) = 7 if e = 2, a(p^e) = 1 otherwise. - Antti Karttunen, Mar 31 2013

From Wesley Ivan Hurt, Jul 09 2016: (Start)

G.f.: x*(1+3*x+x^2+7*x^3)/(1-x^4).

a(n) = a(n-4) for n>3.

a(2n) = 5+2*(-1)^n, a(2n-1) = 1. (End)

MAPLE

seq(op([1, 3, 1, 7]), n=1..50); # Wesley Ivan Hurt, Jul 09 2016

MATHEMATICA

PadRight[{}, 100, {1, 3, 1, 7}] (* Wesley Ivan Hurt, Jul 09 2016 *)

PROG

(PARI) a(n)=1+2*((n-1)%2)*((n-1)%4); \\ Jaume Oliver Lafont, Aug 28 2009; corrected by Antti Karttunen, Mar 31 2013

(PARI) a(n)=[1, 3, 1, 7][1+(n-1)%4]; \\ Joerg Arndt, Apr 02 2013

(MAGMA) &cat [[1, 3, 1, 7]^^30]; // Wesley Ivan Hurt, Jul 09 2016

CROSSREFS

First differences of A112062.

Also half of the first differences of A112072. Cf. A112086.

Sequence in context: A136011 A227984 A021991 * A053381 A038712 A065745

Adjacent sequences:  A112129 A112130 A112131 * A112133 A112134 A112135

KEYWORD

nonn,mult,easy

AUTHOR

Antti Karttunen, Aug 28 2005

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
The OEIS Community | Maintained by The OEIS Foundation Inc.

License Agreements, Terms of Use, Privacy Policy. .

Last modified April 7 13:36 EDT 2020. Contains 333305 sequences. (Running on oeis4.)