cp's OEIS Frontend

This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.

Previous Showing 21-28 of 28 results.

A133675 Negative discriminants with form class number 1 (negated).

Original entry on oeis.org

3, 4, 7, 8, 11, 12, 16, 19, 27, 28, 43, 67, 163
Offset: 1

Views

Author

N. J. A. Sloane, May 16 2003

Keywords

Comments

The list on p. 260 of Cox is missing -12, the list in Theorem 7.30 on p. 149 is correct. - Andrew V. Sutherland, Sep 02 2012
Let b(k) be the number of integer solutions of f(x,y) = k, where f(x,y) is the principal binary quadratic form with discriminant d<0 (i.e., f(x,y) = x^2 - (d/4)*y^2 if 4|d, x^2 + x*y + ((1-d)/4)*y^2 otherwise), then this sequence lists |d| such that {b(k)/b(1): k>=1} is multiplicative. See Crossrefs for the actual sequences. - Jianing Song, Nov 20 2019

References

  • D. A. Cox, Primes of the form x^2+ny^2, Wiley, New York, 1989, pp. 149, 260.
  • D. E. Flath, Introduction to Number Theory, Wiley-Interscience, 1989.

Crossrefs

The sequences {b(k): k>=0}: A004016 (d=-3), A004018 (d=-4), A002652 (d=-7), A033715 (d=-8), A028609 (d=-11), A033716 (d=-12), A004531 (d=-16), A028641 (d=-19), A138805 (d=-27), A033719 (d=-28), A138811 (d=-43), A318984 (d=-67), A318985 (d=-163).
The sequences {b(k)/b(1): k>=1}: A002324 (d=-3), A002654 (d=-4), A035182 (d=-7), A002325 (d=-8), A035179 (d=-11), A096936 (d=-12), A113406 (d=-16), A035171 (d=-19), A138806 (d=-27), A110399 (d=-28), A035147 (d=-43), A318982 (d=-67), A318983 (d=-163).

Programs

  • PARI
    ok(n)={(-n)%4<2 && quadclassunit(-n).no == 1} \\ Andrew Howroyd, Jul 20 2018

Extensions

Corrected by David Brink, Dec 29 2007

A341785 Norms of prime elements in Z[(1+sqrt(-11))/2], the ring of integers of Q(sqrt(-11)).

Original entry on oeis.org

3, 4, 5, 11, 23, 31, 37, 47, 49, 53, 59, 67, 71, 89, 97, 103, 113, 137, 157, 163, 169, 179, 181, 191, 199, 223, 229, 251, 257, 269, 289, 311, 313, 317, 331, 353, 361, 367, 379, 383, 389, 397, 401, 419, 421, 433, 443, 449, 463, 467, 487, 499, 509, 521
Offset: 1

Views

Author

Jianing Song, Feb 19 2021

Keywords

Comments

Also norms of prime ideals in Z[(1+sqrt(-11))/2], which is a unique factorization domain. The norm of a nonzero ideal I in a ring R is defined as the size of the quotient ring R/I.
Consists of the primes congruent to 0, 1, 3, 4, 5, 9 modulo 11 and the squares of primes congruent to 2, 6, 7, 8, 10 modulo 5.
For primes p == 1, 3, 4, 5, 9 (mod 11), there are two distinct ideals with norm p in Z[(1+sqrt(-11))/2], namely (x + y*(1+sqrt(-11))/2) and (x + y*(1-sqrt(-11))/2), where (x,y) is a solution to x^2 + x*y + 3*y^2 = p; for p = 11, (sqrt(-11)) is the unique ideal with norm p; for p == 2, 6, 7, 8, 10 (mod 11), (p) is the only ideal with norm p^2.

Examples

			norm((1 + sqrt(-11))/2) = norm((1 - sqrt(-11))/2) = 3;
norm((3 + sqrt(-11))/2) = norm((3 - sqrt(-11))/2) = 5;
norm((9 + sqrt(-11))/2) = norm((9 - sqrt(-11))/2) = 23;
norm((5 + 3*sqrt(-11))/2) = norm((5 - 3*sqrt(-11))/2) = 31.
		

Crossrefs

The number of nonassociative elements with norm n (also the number of distinct ideals with norm n) is given by A035179.
The total number of elements with norm n is given by A028609.
Norms of prime ideals in O_K, where K is the quadratic field with discriminant D and O_K be the ring of integers of K: A055673 (D=8), A341783 (D=5), A055664 (D=-3), A055025 (D=-4), A090348 (D=-7), A341784 (D=-8), this sequence (D=-11), A341786 (D=-15*), A341787 (D=-19), A091727 (D=-20*), A341788 (D=-43), A341789 (D=-67), A341790 (D=-163). Here a "*" indicates the cases where O_K is not a unique factorization domain.

Programs

  • PARI
    isA341785(n) = my(disc=-11); (isprime(n) && kronecker(disc,n)>=0) || (issquare(n, &n) && isprime(n) && kronecker(disc,n)==-1)

A065099 Weight 5 level 11 cusp form with complex multiplication by Q(sqrt(11)) and trivial character.

Original entry on oeis.org

1, 0, 7, 16, -49, 0, 0, 0, -32, 0, 121, 112, 0, 0, -343, 256, 0, 0, 0, -784, 0, 0, 167, 0, 1776, 0, -791, 0, 0, 0, -553, 0, 847, 0, 0, -512, -2113, 0, 0, 0, 0, 0, 0, 1936, 1568, 0, -1918, 1792, 2401, 0, 0, 0, -718, 0, -5929, 0, 0, 0, 4487, -5488, 0, 0, 0, 4096
Offset: 1

Views

Author

Kok Seng Chua (chuaks(AT)ihpc.nus.edu.sg), Nov 20 2001

Keywords

Comments

This is a member of an infinite family of odd weight level 11 multiplicative modular forms. g_1 = A035179, g_3 = A129522, g_5 = A065099, g_7 = A138661. - Michael Somos, Jun 07 2015

Examples

			G.f. = q + 7*q^3 + 16*q^4 - 49*q^5 - 32*q^9 + 121*q^11 + 112*q^12 - 343*q^15 + ...
		

Crossrefs

Programs

  • Magma
    A := Basis( CuspForms( Gamma1(11), 5), 71); A[1] + 7*A[3] + 16*A[4] - 49*A[5] - 32*A[9] + 121*A[11] + 112*A[12] - 343*A[15]; /* Michael Somos, Aug 26 2015 */
  • Mathematica
    a[ n_] := SeriesCoefficient[ With[{F1 = (QPochhammer[ q] QPochhammer[ q^11])^2, F2 = (QPochhammer[ q^2] QPochhammer[ q^22])^2, F3 = (QPochhammer[ q^2] QPochhammer[ q^22])^3, F4 = (QPochhammer[ q^4] QPochhammer[ q^44])^2}, (F1^4 + 8 q F1^3 F2 + 32 q^2 F1^2 F2^2 + 88 q^3 F1 F2^3 + 64 q^4 F2^4 + 96 q^6 F4 F2^3 + 128 q^5 F1 F4 (F2^2 + q^2 F2 F4 + q^4 F4^2)) / F3], {q, 0, n}]; (* Michael Somos, Jun 07 2015 *)
  • PARI
    { B(N,a,x,y,x2,y2)= a=vector(N); for (x=0,floor(sqrt(4*N)), for (y=0,floor(sqrt(4*N/11)),x2=x*x; y2=y*y; n=(x2+11*y2); if (n%4==0 && n<=4*N && n>0, w=(2*x2*x2-132*x2*y2+242*y2*y2)/32; a[n/4]+=w; if (x*y !=0, a[n/4]+=w)))); a }
    
  • PARI
    {a(n) = my(A, p, e, x, y, a0, a1); if( n<1, 0, A = factor(n); prod( k=1, matsize(A)[1], [p, e] = A[k, ]; if( p==11, 121^e, kronecker( -11, p)==-1, if( e%2, 0, p^(2*e)), for( x=1, sqrtint(4*p\11), if( issquare(4*p - 11*x^2, &y), break)); y = y^4 - 4 * p*y^2 + 2 * p^2; a0=1; a1=y; for( i=2, e, x=y*a1 - p^4*a0; a0=a1; a1=x); a1)))}; /* Michael Somos, Jun 08 2007 */
    
  • PARI
    {a(n) = my(A, F1, F2, F4); if( n<1, 0, n--; A = x * O(x^n); F1 = (eta(x + A) * eta(x^11 + A))^2; F2 = (eta(x^2 + A) * eta(x^22 + A))^2; F4 = (eta(x^4 + A) * eta(x^44 + A))^2; polcoeff( (F1^4 + 8 * x * F1^3*F2 + 32 * x^2 * F1^2*F2^2 + 88 * x^3 * F1*F2^3 + 64 * x^4 * F2^4 + 96 * x^6 * F4*F2^3 + 128 * x^5 * F1*F4 * (F2^2 + x^2 * F2*F4 + x^4 * F4^2)) / (eta(x^2 + A) * eta(x^22 + A))^3, n))}; /* Michael Somos, Jun 08 2007 */
    
  • PARI
    {a(n) = if( n<1, 0, n*=4; sum( y=0, sqrtint(n\11), if( issquare( n - 11 * y^2), if( (n > 11*y^2) && y, 2, 1) * (n^2 - 88 * n*y^2 + 968 * y^4) / 16)))}; /* Michael Somos, Jun 08 2007 */
    

Formula

G.f. is a period 1 Fourier series which satisfies f(-1 / (11 t)) = 11^(5/2) (t/i)^5 f(t) where q = exp(2 Pi i t). - Michael Somos, Jun 08 2007
a(n) is multiplicative with a(11^e) = 121^e, a(p^e) = (1 + (-1)^e) / 2 * p^(2*e) if p == 2, 6, 7, 8, 10 (mod 11), a(p^e) = a(p) * a(p^(e-1)) - p^4 * a(p^(e-2)) if p == 1, 3, 4, 5, 9 (mod 11) where a(p) = y^4 - 4 * p*y^2 + 2 * p^2 and 4*p = y^2 + 11 * x^2. - Michael Somos, Jun 08 2007

A318982 a(n) = Sum_{d|n} Kronecker(-67, d).

Original entry on oeis.org

1, 0, 0, 1, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 1, 2, 0, 2, 0, 0, 0, 2, 0, 1, 0, 0, 0, 2, 0, 0, 0, 0, 0, 0, 1, 2, 0, 0, 0, 0, 0, 0, 0, 0, 0, 2, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 2, 0, 0, 0, 0, 1, 0, 0, 1, 2, 0, 0, 2, 0, 2, 0, 0, 2, 0, 0, 0, 0, 1, 0, 2, 0, 0, 0, 0
Offset: 1

Views

Author

Jianing Song, Sep 06 2018

Keywords

Comments

Coefficients in expansion of Dirichlet series Product_p (1-(Kronecker(m,p)+1)*p^(-s) + Kronecker(m,p)*p^(-2s))^(-1) for m = -67.
Half of the number of integer solutions to x^2 + x*y + 17*y^2 = n. Also, a(n) is the number of integral elements with norm n in Q[sqrt(-67)] counted up to association.
Inverse Moebius transform of A011596.

Examples

			G.f. = x + x^4 + x^9 + x^16 + 2*x^17 + 2*x^19 + 2*x^23 + x^25 + 2*x^29 + x^36 + 2*x^37 + 2*x^47 + x^49 + 2*x^59 + x^64 + x^67 + 2*x^68 + 2*x^71 + 2*x^73 + 2*x^76 + ...
		

Crossrefs

Cf. A318984.
Moebius transform gives A011596.
Number of integral elements with norm n in Q[sqrt(d)] counted up to association: A002324 (d=-3), A002654 (d=-4), A035182 (d=-7), A002325 (d=-8), A035179 (d=-11), A035171 (d=-19), A035147 (d=-43), this sequence (d=-67), A318983 (d=-163).

Programs

  • Mathematica
    a[n_]:=If[n<0, 0, DivisorSum[n, KroneckerSymbol[-67, #] &]];
    Table[a[n], {n, 1, 110}] (* Vincenzo Librandi, Sep 10 2018 *)
  • PARI
    a(n) = sumdiv(n, d, kronecker(-67, d))

Formula

a(n) is multiplicative with a(67^e) = 1, a(p^e) = (1 + (-1)^e) / 2 if Kronecker(-67, p) = -1, a(p^e) = e + 1 if Kronecker(-67, p) = 1.
G.f.: Sum_{k>0} Kronecker(-67, k) * x^k / (1 - x^k).
A318984(n) = 2 * a(n) unless n = 0.
Asymptotic mean: Limit_{m->oo} (1/m) * Sum_{k=1..m} a(k) = Pi/sqrt(67) = 0.383806... . - Amiram Eldar, Dec 16 2023

A318983 a(n) = Sum_{d|n} Kronecker(-163, d).

Original entry on oeis.org

1, 0, 0, 1, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 2, 0, 2, 0, 0, 0, 2, 0, 1, 0, 0, 0, 2, 0, 0, 0, 0, 0, 0, 0, 2, 0, 0, 1, 0, 0, 0, 0, 0, 0, 2, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 2, 0, 0, 0, 0
Offset: 1

Views

Author

Jianing Song, Sep 06 2018

Keywords

Comments

Coefficients in expansion of Dirichlet series Product_p (1-(Kronecker(m,p)+1)*p^(-s) + Kronecker(m,p)*p^(-2s))^(-1) for m = -163.
Half of the number of integer solutions to x^2 + x*y + 41*y^2 = n. Also, a(n) is the number of integral elements with norm n in Q[sqrt(-163)] counted up to association.
Inverse Moebius transform of A011615.

Examples

			G.f. = x + x^4 + x^9 + x^16 + x^25 + x^36 + 2*x^41 + 2*x^43 + 2*x^47 + x^49 + 2*x^53 + 2*x^61 + x^64 + 2*x^71 + ...
		

Crossrefs

Cf. A318985.
Moebius transform gives A011615.
Number of integral elements with norm n in Q[sqrt(d)] counted up to association: A002324 (d=-3), A002654 (d=-4), A035182 (d=-7), A002325 (d=-8), A035179 (d=-11), A035171 (d=-19), A035147 (d=-43), A318982 (d=-67), this sequence (d=-163).

Programs

  • Mathematica
    a[n_] := DivisorSum[n, KroneckerSymbol[-163, #] &]; Array[a, 100] (* Amiram Eldar, Dec 16 2023 *)
  • PARI
    a(n) = sumdiv(n, d, kronecker(-163, d))

Formula

a(n) is multiplicative with a(163^e) = 1, a(p^e) = (1 + (-1)^e) / 2 if Kronecker(-163, p) = -1, a(p^e) = e + 1 if Kronecker(-163, p) = 1.
G.f.: Sum_{k>0} Kronecker(-163, k) * x^k / (1 - x^k).
A318985(n) = 2 * a(n) unless n = 0.
Asymptotic mean: Limit_{m->oo} (1/m) * Sum_{k=1..m} a(k) = Pi/sqrt(163) = 0.246068... . - Amiram Eldar, Dec 16 2023

A129522 Expansion of unique weight 3 level 11 multiplicative cusp form in powers of q.

Original entry on oeis.org

1, 0, -5, 4, -1, 0, 0, 0, 16, 0, -11, -20, 0, 0, 5, 16, 0, 0, 0, -4, 0, 0, 35, 0, -24, 0, -35, 0, 0, 0, -37, 0, 55, 0, 0, 64, -25, 0, 0, 0, 0, 0, 0, -44, -16, 0, 50, -80, 49, 0, 0, 0, -70, 0, 11, 0, 0, 0, 107, 20, 0, 0, 0, 64, 0, 0, 35, 0, -175, 0, -133, 0, 0
Offset: 1

Views

Author

Michael Somos, Apr 19 2007, Jun 06 2007

Keywords

Comments

This is a member of an infinite family of odd weight level 11 multiplicative modular forms. g_1 = A035179, g_3 = A129522, g_5 = A065099, g_7 = A138661.

Examples

			G.f. = q - 5*q^3 + 4*q^4 - q^5 + 16*q^9 - 11*q^11 - 20*q^12 + 5*q^15 + 16*q^16 + ...
		

Crossrefs

Programs

  • Magma
    A := Basis( CuspForms( Gamma1(11), 3), 73); A[1] - 5*A[3] + 4*A[4] - A[5]; /* Michael Somos, Mar 26 2015 */
  • Mathematica
    a[ n_] := Module[ {A, B}, B = QPochhammer[ q] QPochhammer[ q^11]; A = B / (q QPochhammer[ q^3] QPochhammer[ q^33]); SeriesCoefficient[ q B^3 (1 + 3 / A) Sqrt[ q (A + 1 + 3 / A)], {q, 0, n}]]; (* Michael Somos, Mar 26 2015 *)
  • PARI
    {a(n) = my(A, B); if( n<1, 0, n--; A = x * O(x^n); B = eta(x + A) * eta(x^11 + A); A = B /( x * eta(x^3 + A) * eta(x^33 + A)); A = B^3 * (1 + 3/A) * sqrt(x * (A + 1 + 3/A)); polcoeff(A, n))};
    
  • PARI
    {a(n) = my(A, p, e, x, y, a0, a1); if( n<1, 0, A = factor(n); prod( k=1, matsize(A)[1], [p, e] = A[k, ]; if( p==11, (-11)^e, kronecker( -11, p)==-1, if( e%2, 0, p^e), for( x=1, sqrtint(4*p\11), if( issquare(4*p - 11*x^2, &y), break)); y = y^2 - p*2; a0=1; a1=y; for( i=2, e, x = y*a1 - p^2*a0; a0=a1; a1=x); a1)))}; /* Michael Somos, Jun 06 2007 */
    
  • PARI
    {a(n) = my(A); if( n<1, 0, n--; A = x * O(x^n); A = eta(x + A) * eta(x^11 + A); polcoeff( A^2 / subst(A + x * O(x^(n\2)), x, x^2) * (A^2 + 4*x * subst(A + x * O(x^(n\2)), x, x^2)^2 + 8 * x^3 * subst(A + x * O(x^(n\4)), x, x^4)^2), n))}; /* Michael Somos, Jun 06 2007 */
    

Formula

Expansion of (F(q)^2 + 4*F(q^2)^2 + 8*F(q^4)^2) * F(q)^2 / F(q^2) in powers of q where F(q) := eta(q) * eta(q^11) is the g.f. of A030200.
a(n) is multiplicative with a(11^e) = (-11)^e, a(p^e) = (1+(-1)^e)/2*p^e if p == 2, 6, 7, 8, 10 (mod 11), a(p^e) = a(p)*a(p^(e-1)) - p^2*a(p^(e-2)) if p == 1, 3, 4, 5, 9 (mod 11) where a(p) = y^2 - 2*p and 4*p = y^2 + 11*x^2.
G.f. is a period 1 Fourier series which satisfies f(-1 / (11 t)) = 11^(3/2) (t/i)^3 f(t) where q = exp(2 Pi i t).
G.f.: (1/2) * Sum_{u, v in Z} (u*u - 3*v*v) * x^(u*u + u*v + 3*v*v). - Michael Somos, Jun 14 2007
Convolution of A006571 and A028609. - Michael Somos, Aug 14 2012
a(4*n + 2) = 0. - Michael Somos, Nov 11 2015

A138661 Expansion of a level 11 weight 7 multiplicative modular form in powers of q.

Original entry on oeis.org

1, 0, 10, 64, 74, 0, 0, 0, -629, 0, -1331, 640, 0, 0, 740, 4096, 0, 0, 0, 4736, 0, 0, -12670, 0, -10149, 0, -13580, 0, 0, 0, 56018, 0, -13310, 0, 0, -40256, 87050, 0, 0, 0, 0, 0, 0, -85184, -46546, 0, -206350, 40960, 117649, 0, 0, 0, 246890, 0, -98494, 0, 0, 0, 107642, 47360, 0
Offset: 1

Views

Author

Michael Somos, Mar 25 2008

Keywords

Comments

This is a member of an infinite family of odd weight level 11 multiplicative modular forms. g_1 = A035179, g_3 = A129522, g_5 = A065099, g_7 = A138661. - Michael Somos, Jun 07 2015

Examples

			G.f. = q + 10*q^3 + 64*q^4 + 74*q^5 - 629*q^9 - 1331*q^11 + 640*q^12 + 740*q^15 + ...
		

Crossrefs

Programs

  • Magma
    A := Basis( CuspForms( Gamma1(11), 7), 58); A[1] + 10*A[3] + 64*A[4] + 74*A[5] - 629*A[9] - 1331*A[11] + 640*A[12] + 740*A[15] + 4096*A[16] + 4736*A[20] - 12670*A[23]; /* Michael Somos, Jun 07 2015 */
  • PARI
    {a(n) = my(A, p, e, x, y, a0, a1); if( n<1, 0, A = factor(n); prod(k=1, matsize(A)[1], [p, e] = A[k, ]; if( p==11, (-1331)^e, kronecker(-11, p)==-1, if(e%2, 0, (p^3)^e), for(x=1, sqrtint(4*p\11), if( issquare(4*p - 11*x^2, &y), break)); y = y^6 - 6*p*y^4 + 9*p^2*y^2 - 2*p^3; a0=1; a1=y; for(i=2, e, x = y * a1 - p^6 * a0; a0=a1; a1=x); a1)))};
    
  • PARI
    {a(n) = my(A, F1, F2, G1); if( n<1, 0, A = x * O(x^n); F1 = x * (eta(x + A) * eta(x^11 + A))^2; F2 = x * eta(x^2 + A) * eta(x^22 + A); G1 = (F1 + 4 * F2^2 + 8 * x^4 * (eta(x^4 + A) * eta(x^44 + A))^2) / F2; polcoeff( G1 * F1 * (G1^4 - 8*G1^2*F1 + 7*F1^2), n))};
    

Formula

a(4*n + 2) = a(11*n + 2) = a(11*n + 6) = a(11*n + 7) = a(11*n + 8) = a(11*n + 10) = 0.
a(n) is multiplicative with a(11^e) = (-1331)^e, a(p^e) = p^(3*e) * (1 + (-1)^e) / 2 if p == 2, 6, 7, 8, 10 (mod 11), a(p^e) = a(p) * a(p^(e-1)) - p^6 * a(p^(e-2)) if p == 1, 3, 4, 5, 9 (mod 11) where a(p) = y^6 - 6*p*y^4 + 9*p^2*y^2 - 2*p^3 and 4 * p = y^2 + 11 * x^2.
G.f. is a period 1 Fourier series which satisfies f(-1 / (11 t)) = 11^(7/2) (t/i)^7 f(t) where q = exp(2 Pi i t).

A035247 Indices of the nonzero terms in expansion of Dirichlet series Product_p (1-(Kronecker(m,p)+1)*p^(-s)+Kronecker(m,p)*p^(-2s))^(-1) for m= -11.

Original entry on oeis.org

1, 3, 4, 5, 9, 11, 12, 15, 16, 20, 23, 25, 27, 31, 33, 36, 37, 44, 45, 47, 48, 49, 53, 55, 59, 60, 64, 67, 69, 71, 75, 80, 81, 89, 92, 93, 97, 99, 100, 103, 108, 111, 113, 115, 121, 124, 125, 132, 135, 137, 141, 144, 147, 148, 155, 157, 159, 163, 165, 169, 176, 177, 179, 180, 181, 185, 188, 191, 192, 196, 199
Offset: 1

Views

Author

Keywords

Crossrefs

Cf. A028954 (a probable duplicate). [From R. J. Mathar, Oct 20 2008]
Cf. A035179 (the expansion itself).

Programs

  • Mathematica
    Reap[For[n = 1, n < 200, n++, r = Reduce[x^2 + x y + 3 y^2 == n, {x, y}, Integers]; If[r =!= False, Sow[n]]]][[2, 1]] (* Jean-François Alcover, Oct 31 2016 *)
  • PARI
    m=-11; select(x -> x, direuler(p=2,101,1/(1-(kronecker(m,p)*(X-X^2))-X)), 1) \\ Fixed by Andrey Zabolotskiy, Jul 30 2020

Extensions

More terms from Jean-François Alcover, Oct 31 2016
Name corrected by Andrey Zabolotskiy, Jul 30 2020
Previous Showing 21-28 of 28 results.