A214664 The x-coordinates of prime numbers in an Ulam spiral oriented counterclockwise with first step east.

1, 1, -1, -1, 2, 2, -2, -2, 0, 3, 3, -3, -3, -3, 1, 4, 2, 0, -4, -4, -4, 2, 5, 5, -1, -5, -5, -5, -5, -3, 6, 6, 2, 0, -6, -6, -6, 0, 4, 7, 7, 7, -1, -3, -7, -7, -7, 5, 8, 8, 8, 8, 8, -2, -8, -8, -8, -8, -4, 0, 2, 9, 9, 5, 3, -1, -9, -9, -5, -3, 1, 7, 10, 10

Offset

1,5

Comments

The eight possible orientations of the Ulam spiral can be derived by combining either A214664 or A214666 with either A214665 or A214667 as ordered pairs of coordinates.

Links

William Rex Marshall, Table of n, a(n) for n = 1..10077 (coordinates of primes in a 325 X 325 square).

Scientific American, Front Matter, Vol. 210, No. 3, March 1964.

Crossrefs

Cf. A000040, A063826, A214665, A214666, A214667.

Sequence in context: A171932 A358094 A305629 * A214666 A320471 A333180

Adjacent sequences: A214661 A214662 A214663 * A214665 A214666 A214667

Keyword

sign,easy

Author

William Rex Marshall, Jul 26 2012

Status

approved