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!)
A340944 List of X-coordinates of point moving along one of the arms of a counterclockwise square spiral with four arms; A340945 gives Y-coordinates. 2
0, 1, 1, 1, 0, -1, -2, -3, -3, -3, -3, -3, -3, -3, -2, -1, 0, 1, 2, 3, 4, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 4, 3, 2, 1, 0, -1, -2, -3, -4, -5, -6, -7, -7, -7, -7, -7, -7, -7, -7, -7, -7, -7, -7, -7, -7, -7, -6, -5, -4, -3, -2, -1, 0, 1, 2, 3, 4, 5, 6, 7, 8, 9 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,7

LINKS

Rémy Sigrist, Table of n, a(n) for n = 0..10101

Rémy Sigrist, PARI program for A340944

Index entries for sequences related to coordinates of 2D curves

FORMULA

a(n) = A340945(n) iff n belongs to A002939.

a(n) = - A340945(n) iff n = 4*x^2 - 6*x + 2 for some x.

a(n) = 0 iff n is an even square (A016742).

EXAMPLE

The spiral starts as follows:

     +-----+-----+-----+-----+

     |7     6     5     4    |3    .

     |                       |     .

     +     +-----+-----+     +     +

     |8    |           |     |2    |

     |     |           |     |     |

     +     +     +-----+-----+     +

     |9    |     |     |0     1    |

     |     |     |     |           |     .

     +     +     +     +-----+-----+     .

     |10   |     |                       .

     |     |     |                       .

     +     +     +-----+-----+-----+-----+

     .11   .

     .

- so a(0) = a(4) = 0,

     a(1) = a(2) = a(3) = 1,

     a(5) = -1,

     a(6) = -2,

     a(7) = a(8) = a(9) = a(10) = a(11) = -3.

PROG

(PARI) See Links section.

CROSSREFS

Cf. A002939, A016742, A340171, A340945.

Sequence in context: A247656 A294081 A192454 * A270533 A344511 A244919

Adjacent sequences:  A340941 A340942 A340943 * A340945 A340946 A340947

KEYWORD

sign,look

AUTHOR

Rémy Sigrist, Jan 30 2021

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 July 30 12:08 EDT 2021. Contains 346359 sequences. (Running on oeis4.)