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A096447 Odd primes p such that the number of primes less than p equal to 1 mod 4 is equal to the number of primes less than p equal to 3 mod 4. 18
3, 7, 19, 43, 463, 26839, 26861, 26879, 26891, 26903, 26927, 616783, 616799, 616841, 616849, 616877, 617039, 617269, 617369, 617401, 617429, 617453, 617471, 617479, 617521, 617537, 617587, 617689, 617717, 617723, 618439, 618547, 618619, 618643 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

First term prime(2) = 3 is placed on 0th row.

If prime(n-1) = +1 mod 4 is on k-th row then we put prime(n) on (k-1)-st row.

If prime(n-1) = -1 mod 4 is on k-th row then we put prime(n) on (k+1)-st row.

This process makes an array of prime numbers:

3, 7, 19, 43, ....0th row (this sequence)

5, 11, 17, 23, 31, 41, 47, 59, 67, 103, 127, .... first row (A096448)

13, 29, 37, 53, 61, 71, 79, 101, 107, 113 .... 2nd row (A096451)

73, 83, 97, 109, .... 3rd row

89, .... 4th row

This is the next prime after A007351. - Joshua Zucker, May 03 2006

LINKS

Giovanni Resta, Table of n, a(n) for n = 1..10000

MATHEMATICA

lim = 10^5; k1 = 0; k3 = 0; p = 2; t = {}; Do[p = NextPrime[p]; If[k1 == k3, AppendTo[t, p]]; If[Mod[p, 4] == 1, k1++, k3++], {lim}]; t (* T. D. Noe, Sep 07 2011 *)

CROSSREFS

Cf. A096448-A096455.

Cf. A007351, A096448-A096455.

Sequence in context: A136041 A146685 A146653 * A274596 A185696 A141344

Adjacent sequences:  A096444 A096445 A096446 * A096448 A096449 A096450

KEYWORD

nonn,easy

AUTHOR

Yasutoshi Kohmoto, Aug 12 2004

EXTENSIONS

More terms from Joshua Zucker, May 03 2006

Added "odd" to definition. - N. J. A. Sloane, Sep 09 2015

STATUS

approved

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Last modified March 28 17:51 EDT 2020. Contains 333103 sequences. (Running on oeis4.)