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

 

Logo

Annual appeal: Please make a donation to keep the OEIS running! Over 6000 articles have referenced us, often saying "we discovered this result with the help of the OEIS".
Other ways to donate

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 November 23 19:08 EST 2017. Contains 295128 sequences.