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

 

Logo


Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A104862 First differences of A014292. 12
0, 1, 1, 1, 1, 0, -2, -5, -9, -13, -15, -12, 0, 25, 65, 117, 169, 196, 158, 3, -321, -841, -1519, -2200, -2560, -2079, -79, 4121, 10881, 19720, 28638, 33435, 27351, 1547, -52895, -140772, -256000, -372775, -436655, -359763, -26871 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,7

COMMENTS

Real part of the sequence of complex numbers defined by c(0) = 1, c(1) = 1, for n>1 c(n) = c(n-1) + i*c(n-2).

a(n) = real part of the sequence b of quaternions defined by b(0)=1,b(1)=1, b(n) = b(n-1) + b(n-2)*(0,s,s,s) where s = 1/sqrt(3).

LINKS

Table of n, a(n) for n=0..40.

FORMULA

G.f.: Re(1/(1-x-ix^2))=(1-x)/(1-2x+x^2+x^4). - Paul Barry, Apr 25 2005

a(n)=sum{k=0..floor(n/2), C(n-k, k)cos(pi*k/2)}. - Paul Barry, Apr 25 2005

a(0)=0, a(1)=1, a(n+1) = a(n) - Sum_{k=0..n-3} a(k). - Alex Ratushnyak, May 03 2012

PROG

(Python)

a = [0]*1000

a[1]=1

for n in range(1, 55):

.    print a[n-1],

.    sum=0

.    for k in range(n-2):

.    .    sum+=a[k]

.    a[n+1] = a[n]-sum

# from Alex Ratushnyak, May 03 2012

CROSSREFS

Cf. A078001, A014292.

Sequence in context: A218706 A270950 A139405 * A190686 A247986 A259252

Adjacent sequences:  A104859 A104860 A104861 * A104863 A104864 A104865

KEYWORD

sign

AUTHOR

Gerald McGarvey, Apr 24 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 | More pages
The OEIS Community | Maintained by The OEIS Foundation Inc.

License Agreements, Terms of Use, Privacy Policy .

Last modified June 28 17:16 EDT 2017. Contains 288839 sequences.