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A053999 Prime number spiral (clockwise, Northwest spoke). 9
2, 23, 97, 227, 419, 661, 1009, 1427, 1879, 2437, 3083, 3803, 4637, 5519, 6481, 7573, 8737, 9931, 11321, 12743, 14327, 15877, 17609, 19471, 21391, 23327, 25469, 27739, 30047, 32429, 34849, 37501, 40231, 42943, 45989, 49037, 52121, 55381, 58579 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,1

COMMENTS

Largest prime in n-th shell of prime spiral.

Shell 1 comprises the primes 3 5 7 11 13 17 19 23; 3 is lowest, 23 is highest.

LINKS

Ivan Panchenko, Table of n, a(n) for n = 0..1000

FORMULA

8-spoke wheel overlays prime number spiral; hub is 2 in shell 0; 8 spokes radiate from this hub; this is Northwest, clockwise.

EXAMPLE

Begin a prime number spiral at shell 0 (prime 2), proceed clockwise, Northwest.

MATHEMATICA

Table[ Prime[4n^2 + 4n + 1], {n, 0, 40} ]

CROSSREFS

Cf. A016754, A054551, A054553, A054555, A054564, A054566, A054566, A054570.

Sequence in context: A270868 A239186 A238185 * A131176 A141405 A068876

Adjacent sequences:  A053996 A053997 A053998 * A054000 A054001 A054002

KEYWORD

easy,nonn

AUTHOR

Enoch Haga and G. L. Honaker, Jr., Apr 10 2000

EXTENSIONS

Edited by Robert G. Wilson v, Feb 25 2002

STATUS

approved

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Last modified December 3 04:39 EST 2016. Contains 278698 sequences.