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Revision History for A321865

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Showing entries 1-10 | older changes
a(n) = A321860(prime(n)).
(history; published version)
#17 by Michael De Vlieger at Sun Nov 19 10:23:38 EST 2023
STATUS

proposed

approved

#16 by Peter Munn at Sun Nov 19 10:10:08 EST 2023
STATUS

editing

proposed

#15 by Peter Munn at Sun Nov 19 05:52:30 EST 2023
COMMENTS

In general, assuming the strong form of RH, if 0 < a, b < k are integers, gcd(a, k) = gcd(b, k) = 1, a is a quadratic residue and b is a quadratic nonresidue mod n, then Pi(k,b)(n) > Pi(k,a)(n) occurs more often than not. Pi(a,b)(x) denotes the number of primes in the arithmetic progression a*k + b less than or equal to x. This phenomenon is called "Chebyshev's bias".

Please see the comment in A321856 describing "Chebyshev's bias" in the general case.

STATUS

approved

editing

Discussion
Sun Nov 19
05:54
Peter Munn: Rationale as for the recent amendment to A321857.
#14 by N. J. A. Sloane at Sat Nov 24 13:22:14 EST 2018
STATUS

proposed

approved

#13 by Jianing Song at Sat Nov 24 09:14:27 EST 2018
STATUS

editing

proposed

#12 by Jianing Song at Sat Nov 24 09:14:23 EST 2018
COMMENTS

In general, assuming the strong form of RH, if 0 < a, b < k are integers, gcd(a, k) = gcd(b, k) = 1, a is a quadratic residue and b is a quadratic nonresidue mod n, then Pi(k,b)(n) > Pi(k,a)(n) occurs more often than not. This phenomenon is called "Chebyshev's bias". Pi(a,b)(x) denotes thenumber the number of primes in the arithmetic progression a*k + b less than or equal to x. This phenomenon is called "Chebyshev's bias".

#11 by Jianing Song at Sat Nov 24 09:08:07 EST 2018
COMMENTS

In general, assuming the strong form of RH, if 0 < a, b < k are integers, gcd(a, k) = gcd(b, k) = 1, a is a quadratic residue and b is a quadratic nonresidue mod n, then Pi(k,b)(n) > Pi(k,a)(n) occurs more often than not. This phenomenon is called "Chebyshev's bias". Pi(a,b)(x) denotes thenumber of primes in the arithmetic progression a*k + b less than or equal to x. This phenomenon is called "Chebyshev's bias".

#10 by Jianing Song at Sat Nov 24 09:07:36 EST 2018
DATA

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

STATUS

proposed

editing

#9 by Jianing Song at Sat Nov 24 09:07:03 EST 2018
STATUS

editing

proposed

#8 by Jianing Song at Sat Nov 24 09:06:00 EST 2018
COMMENTS

Among the first 10000 terms there are only 32 negative ones.

In general, assuming the strong form of RH, if 0 < a, b < k are integers, gcd(a, k) = gcd(b, k) = 1, a is a quadratic residue and b is a quadratic nonresidue mod n, then Pi(k,b)(n) > Pi(k,a)(n) occurs more often than not. This phenomenon is called "Chebyshev's bias". Pi(a,b)(x) denotes thenumber of primes in the arithmetic progression a*k + b less than or equal to x. This phenomenon is called "Chebyshev's bias".

LINKS

Wikipedia, <a href="https://en.wikipedia.org/wiki/Chebyshev%27s_bias">Chebyshev's bias</a>

FORMULA

a(n) = -Sum_{primes p<=n} Legendre(prime(i),11) = -Sum_{primes p<=n} Kronecker(-11,prime(i)) = -Sum_{i=1..n} A011582(prime(i)).

EXAMPLE

prime(46) = 199. Among the primes <= 199, there are 20 ones congruent to 1, 3, 4, 5, 9 modulo 11 and 23 ones congruent to 2, 6, 7, 8, 10 modulo 11, so a(46) = 23 - 20 = 3.

PROG

(PARI) a(n) = -sum(i=1, n, kronecker(-11, prime(i)))

CROSSREFS

Cf. A011582.

Sequences of the form "a(n) = -Sum_{i=1..n} Kronecker(d,prime(i))" with |d| <= 12: A321865 this sequence (d=-11), A320858 (d=-8), A321864 (d=-7), A038698 (d=-4), A112632 (d=-3), A321862 (d=5), A321861 (d=8), A321863 (d=12).