A112053 -id:A112053 - cp's OEIS frontend

A112054 Indices where A112053 is not zero.

12, 18, 30, 42, 48, 72, 78, 90, 102, 108, 120, 132, 138, 162, 168, 180, 192, 198, 210, 222, 228, 240, 252, 258, 282, 288, 300, 312, 318, 330, 342, 348, 372, 378, 390, 402, 408, 420, 432, 438, 450, 462, 468, 492, 498, 510, 522, 528, 540, 552, 558, 582, 588

Offset: 1

Antti Karttunen, Aug 27 2005

nonn

These are all divisible by 6, as J(2,m) = +1 if m = 1 or 7 mod 8 and -1 if m = 3 or 5 mod 8 and J(3,m) = +1 if m = 1 or 11 mod 12, -1 if m = 5 or 7 mod 12 and 0 if m = 3 or 9 mod 12 (where Jacobi symbol J(i,m) returns +1 if i is quadratic residue modulo odd number m), it follows that only when i=24*n it holds that J(2,i-1)=J(2,i+1)=J(3,i-1)=J(3,i+1)=+1 and thus only then the function A112046 (and A112053) depends on values of J(k>3,m).

Cf. A112058(n) = 4*a(n). A112055(n) = a(n)/6.

a112046[n_]:=Block[{i=1}, While[JacobiSymbol[i, 2n + 1]==1, i++]; i]; Select[Range[1000], a112046[2#] - a112046[2# - 1] != 0 &] (* Indranil Ghosh, May 24 2017 *)

from sympy import jacobi_symbol as J
def a112046(n):
    i=1
    while True:
        if J(i, 2*n + 1)!=1: return i
        else: i+=1
def a(n): return a112046(2*n) - a112046(2*n - 1)
print([n for n in range(1, 1001) if a(n)!=0]) # Indranil Ghosh, May 24 2017

A112059 Nonzero terms of A112053 and A112080.

Original entry on oeis.org

2, -2, 4, 8, -2, 12, -6, 12, 2, -2, -6, 18, -6, 2, -6, -4, 2, -2, 18, 2, -2, 24, 6, -2, 6, -8, 4, 2, -2, -6, 32, -6, 2, -6, -10, 2, -2, 28, 2, -2, 4, 38, -2, 6, -6, 4, 2, -2, -4, 42, -6, 2, -8, -4, 2, -2, 2, -2, 6, 8, -2, 48, -6, 4, 2, -2, -10, 6, -12, 2, -6, -4, 2, -2, 2, -2, 52, 8

Offset: 1

Antti Karttunen, Aug 27 2005

sign

Antti Karttunen, Table of n, a(n) for n = 1..4096

Cf. A112053, A112054, A112080.

from sympy import jacobi_symbol as J
def a112046(n):
    i=1
    while True:
        if J(i, 2*n + 1)!=1: return i
        else: i+=1
def a(n): return a112046(2*n) - a112046(2*n - 1)
print([a(n) for n in range(1, 201) if a(n)!=0]) # Indranil Ghosh, May 25 2017

a(n) = A112053(A112054(n)).

A112046 a(n) = the least k >= 1 for which the Jacobi symbol J(k,2n+1) is not +1 (thus is either 0 or -1).

Original entry on oeis.org

2, 2, 3, 3, 2, 2, 3, 3, 2, 2, 5, 5, 2, 2, 3, 3, 2, 2, 3, 3, 2, 2, 5, 7, 2, 2, 3, 3, 2, 2, 3, 3, 2, 2, 7, 5, 2, 2, 3, 3, 2, 2, 3, 3, 2, 2, 5, 5, 2, 2, 3, 3, 2, 2, 3, 3, 2, 2, 7, 11, 2, 2, 3, 3, 2, 2, 3, 3, 2, 2, 5, 5, 2, 2, 3, 3, 2, 2, 3, 3, 2, 2, 5, 13, 2, 2, 3, 3, 2, 2, 3, 3, 2, 2, 7, 5, 2, 2, 3, 3, 2, 2

Offset: 1

Antti Karttunen, Aug 27 2005

nonn

If we instead list the least k >= 1, for which Jacobi symbol J(k,2n+1) is 0, we get A090368.

It is easy to see that every term is prime. Because the Jacobi symbol is multiplicative as J(ab,m) = J(a,m)*J(b,m) and if for every index i>=1 and < x, J(i,m)=1, then if J(x,m) is 0 or -1, x cannot be composite (say y*z, with both y and z less than x), as then either J(y,m) or J(z,m) would be non-one, which contradicts our assumption that x is the first index where non-one value appears. Thus x must be prime.

Indranil Ghosh and A.H.M. Smeets, Table of n, a(n) for n = 1..20000 (first 1000 terms from Indranil Ghosh)

One more than A112050.
Bisections: A112047, A112048, and their difference: A112053.
Cf. A000040, A053760, A053761, A090368, A112049, A112060, A112070, A268829, A286465, A286466.

A112046(n) = for(i=1, (2*n), if((kronecker(i, (n+n+1)) < 1), return(i))); \\ Antti Karttunen, May 26 2017

from sympy import jacobi_symbol as J
def a(n):
    i=1
    while True:
        if J(i, 2*n + 1)!=1: return i
        else: i+=1
print([a(n) for n in range(1, 103)]) # Indranil Ghosh, May 11 2017

a(n) = A112050(n) + 1 = A000040(A112049(n)).

A112047 Bisection of A112046.

Original entry on oeis.org

2, 3, 2, 3, 2, 5, 2, 3, 2, 3, 2, 5, 2, 3, 2, 3, 2, 7, 2, 3, 2, 3, 2, 5, 2, 3, 2, 3, 2, 7, 2, 3, 2, 3, 2, 5, 2, 3, 2, 3, 2, 5, 2, 3, 2, 3, 2, 7, 2, 3, 2, 3, 2, 5, 2, 3, 2, 3, 2, 7, 2, 3, 2, 3, 2, 5, 2, 3, 2, 3, 2, 5, 2, 3, 2, 3, 2, 11, 2, 3, 2, 3, 2, 5, 2, 3, 2, 3, 2, 7, 2, 3, 2, 3, 2, 5, 2, 3, 2, 3, 2, 5

Offset: 1

Antti Karttunen, Aug 27 2005

nonn

Indranil Ghosh, Table of n, a(n) for n = 1..1000

Cf. A112046, A112048, A112053.

a112046[n_]:=Block[{i=1},While[JacobiSymbol[i, 2n + 1]==1, i++]; i]; Table[a112046[2n - 1], {n, 102}] (* Indranil Ghosh, May 11 2017 *)

from sympy import jacobi_symbol as J
def a112046(n):
    i=1
    while True:
        if J(i, 2*n + 1)!=1: return i
        else: i+=1
print([a112046(2*n - 1) for n in range(1, 103)]) # Indranil Ghosh, May 11 2017

a(n) = A112046(2n-1)

A112048 Bisection of A112046.

Original entry on oeis.org

2, 3, 2, 3, 2, 5, 2, 3, 2, 3, 2, 7, 2, 3, 2, 3, 2, 5, 2, 3, 2, 3, 2, 5, 2, 3, 2, 3, 2, 11, 2, 3, 2, 3, 2, 5, 2, 3, 2, 3, 2, 13, 2, 3, 2, 3, 2, 5, 2, 3, 2, 3, 2, 5, 2, 3, 2, 3, 2, 7, 2, 3, 2, 3, 2, 5, 2, 3, 2, 3, 2, 17, 2, 3, 2, 3, 2, 5, 2, 3, 2, 3, 2, 5, 2, 3, 2, 3, 2, 19, 2, 3, 2, 3, 2, 5, 2, 3, 2, 3, 2

Offset: 1

Antti Karttunen, Aug 27 2005

nonn

Vincenzo Librandi, Table of n, a(n) for n = 1..1000

Cf. A112046, A112047, A112053.

a112046[n_]:=Block[{i=1}, While[JacobiSymbol[i, 2n + 1]==1, i++]; i]; Table[a112046[2n] , {n, 101}] (* Indranil Ghosh, May 24 2017 *)

from sympy import jacobi_symbol as J
def a112046(n):
    i=1
    while True:
        if J(i, 2*n + 1)!=1: return i
        else: i+=1
def a(n): return a112046(2*n)
print([a(n) for n in range(1, 102)])  # Indranil Ghosh, May 24 2017

a(n) = A112046(2n).

cp's OEIS Frontend

A112054 Indices where A112053 is not zero.

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A112059 Nonzero terms of A112053 and A112080.

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A112046 a(n) = the least k >= 1 for which the Jacobi symbol J(k,2n+1) is not +1 (thus is either 0 or -1).

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A112047 Bisection of A112046.

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A112048 Bisection of A112046.

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