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A096448 Primes p such that the number of primes less than p equal to 1 mod 4 is one less than the number of primes less than p equal to 3 mod 4. 13
5, 11, 17, 23, 31, 41, 47, 59, 67, 103, 127, 419, 431, 439, 461, 467, 1259, 1279, 1303, 26833, 26849, 26881, 26893, 26921, 26947, 615883, 616769, 616787, 616793, 616829, 617051, 617059, 617087, 617257, 617473, 617509, 617647, 617681, 617731, 617819 (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

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

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

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

89, ....4th row

LINKS

Table of n, a(n) for n=1..40.

MATHEMATICA

Prime[#]&/@(Flatten[Position[Accumulate[If[Mod[#, 4]==1, 1, -1]&/@ Prime[ Range[ 2, 51000]]], -1]]+2) (* Harvey P. Dale, Mar 08 2015 *)

CROSSREFS

Cf. A096447-A096455.

Cf. A096448-A096455.

Sequence in context: A189938 A184525 A252596 * A147305 A049755 A096449

Adjacent sequences:  A096445 A096446 A096447 * A096449 A096450 A096451

KEYWORD

nonn,easy

AUTHOR

Yasutoshi Kohmoto, Aug 12 2004

EXTENSIONS

More terms from Joshua Zucker, May 03 2006

STATUS

approved

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Last modified March 31 18:53 EDT 2020. Contains 333151 sequences. (Running on oeis4.)