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.

Showing 1-6 of 6 results.

A257402 Expansion of chi(x) * psi(-x^3) * psi(x^12) in powers of x where psi(), chi() are Ramanujan theta functions.

Original entry on oeis.org

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

Views

Author

Michael Somos, Apr 21 2015

Keywords

Comments

Ramanujan theta functions: f(q) (see A121373), phi(q) (A000122), psi(q) (A010054), chi(q) (A000700).

Examples

			G.f. = 1 + x + x^5 + x^8 + x^12 + x^13 + x^16 + x^17 + x^20 + x^21 + x^28 + ...
G.f. = q^11 + q^17 + q^41 + q^59 + q^83 + q^89 + q^107 + q^113 + q^131 + ...

Links

Crossrefs

Cf. A255318, A255319.

Programs

  • Mathematica
    a[ n_] := SeriesCoefficient[ QPochhammer[ -x, x^2] EllipticTheta[ 2, 0, x^6] EllipticTheta[ 2, Pi/4, x^(3/2)] / (2^(3/2) x^(15/8)), {x, 0, n}];
  • PARI
    {a(n) = my(A); if( n<0, 0, A = x * O(x^n); polcoeff( eta(x^2 + A)^2 * eta(x^3 + A) * eta(x^24 + A)^2 / (eta(x + A) * eta(x^4 + A) * eta(x^6 + A)), n))};

Formula

Expansion of q^(-11/6) * eta(q^2)^2 * eta(q^3) * eta(q^24)^2 / (eta(q) * eta(q^4) * eta(q^6)) in powers of q.
a(4*n) = A255318(n). a(4*n + 1) = A255319(n). a(4*n + 2) = a(4*n + 3) = 0.

A256574 Expansion of chi(x) * psi(-x^3) * psi(x^48) in powers of x where psi(), chi() are Ramanujan theta functions.

Original entry on oeis.org

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

Views

Author

Michael Somos, Apr 22 2015

Keywords

Comments

Ramanujan theta functions: f(q) (see A121373), phi(q) (A000122), psi(q) (A010054), chi(q) (A000700).

Examples

			G.f. = 1 + x + x^5 + x^8 + x^16 + x^21 + x^33 + x^40 + x^48 + x^49 + ...
G.f. = q^19 + q^22 + q^34 + q^43 + q^67 + q^82 + q^118 + q^139 + q^163 + ...

Links

Crossrefs

Cf. A255317, A255318, A255319, A255320, A257402, A257403, A263767.

Programs

  • Mathematica
    a[ n_] := SeriesCoefficient[ QPochhammer[ -x, x^2] EllipticTheta[ 2, Pi/4, x^(3/2)] EllipticTheta[ 2, 0, x^24] / (2^(3/2) x^(51/8)), {x, 0, n}];
a[ n_] := If[ n < 0 || Mod[n, 8] == 2, 0, (1/2) Times @@ (Which[# < 5, Boole[# + #2 == 3], Mod[#, 8] > 4, Mod[#2 + 1, 2], True, #2 + 1] & @@@ FactorInteger[ 3 n + 19])]; (* Michael Somos, Oct 25 2015 *)
  • PARI
    {a(n) = my(A, p, e); if( n<0 || n%8 == 2, 0, A = factor(3*n + 19); 1/2 * prod( k=1, matsize(A)[1], [p, e] = A[k, ]; if( p<5, p+e==3, p%8 > 4, 1-e%2, e+1)))};
  • PARI
    {a(n) = my(A); if( n<0, 0, A = x * O(x^n); polcoeff( eta(x^2 + A)^2 * eta(x^3 + A) * eta(x^12 + A) * eta(x^96 + A)^2 / (eta(x + A) * eta(x^4 + A) * eta(x^6 + A) * eta(x^48 + A)), n))};

Formula

Expansion of q^(-19/3) * eta(q^2)^2 * eta(q^3) * eta(q^12) * eta(q^96)^2 / (eta(q) * eta(q^4) * eta(q^6) * eta(q^48)) in powers of q.
Euler transform of a period 96 sequence.
2 * a(n) = A257403(3*n + 19) unless n == 2 (mod 8).
a(4*n + 2) = a(4*n + 3) = a(8*n + 4) = a(16*n + 9) = a(16*n + 13) = 0.
a(4*n + 1) = A257402(n). a(8*n) = A255317(n). a(16*n + 1) = A255318(n). a(16*n + 5) = A255319(n).
a(n) = (-1)^n * A255320(n). - Michael Somos, Apr 24 2015
Expansion of f(x, x^5) * psi(x^48) in powers of x where psi(), f() are Ramanujan theta functions. - Michael Somos, Oct 25 2015
G.f. is a period 1 Fourier series which satisfies f(-1 / (288 t)) = 8^(1/2) (t/i) g(t) where q = exp(2 Pi i t) and g() is the g.f. for A263767.

A257403 Multiplicative with a(2) = 1, a(2^e) = 0 if e>1, a(3^e) = 0^e, a(p^e) = e+1 if p == 1, 3 (mod 8), a(p^e) = (1 + (-1)^e) / 2 if p == 5, 7 (mod 8).

Original entry on oeis.org

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

Views

Author

Michael Somos, Apr 21 2015

Keywords

Examples

			G.f. = x + x^2 + 2*x^11 + 2*x^17 + 2*x^19 + 2*x^22 + x^25 + 2*x^34 + ...

Links

Crossrefs

Cf. A255317, A255318, A255319, A256505, A256574, A257398, A257399, A257402, A257477.

Programs

  • Mathematica
    a[ n_] := If[ n < 2, Boole[n == 1], Times @@ (Which[ # == 2, Boole[#2 == 1], # == 3, 0, Mod[#, 8] < 4, #2 + 1, True, Mod[#2 + 1, 2]]& @@@ FactorInteger[n])];
  • PARI
    {a(n) = my(A, p, e); if( n<1, 0, A = factor(n); prod( k=1, matsize(A)[1], [p, e] = A[k,]; if( p<5, p+e==3, p%8 > 4, 1-e%2, e+1)))};

Formula

Moebius transform is the period 288 sequence A257477.
a(3*n) = a(4*n) = a(8*n + 5) = a(8*n + 7) = 0. a(2*n + 1) = a(4*n + 2).
a(6*n + 1) = A257399(n). a(6*n + 5) = 2*A257402(n).
a(24*n + 1) = A257398(n). a(24*n + 11) = 2*A255318(n). a(24*n + 17) = 2*A255319(n). a(24*n + 19) = 2*A255317(n).
From Michael Somos, Apr 22 2015: (Start)
a(3*n + 2) = A256505(n) unless n == 5 (mod 8). a(3*n + 19) = 2 * A256574(n) unless n == 2 (mod 8).
Expansion of F(q) + F(q^2) + G(q) + G(q^2) in powers of q where F(q) = q * A257399(q^6) and G(q) = 2 * q^11 * A257402(q^6). (End)
Asymptotic mean: Limit_{m->oo} (1/m) * Sum_{k=1..m} a(k) = Pi/(6*sqrt(2)) = 0.370240... . - Amiram Eldar, Oct 17 2022

A258747 Expansion of chi(-x) * f(x^3) * f(-x^6) in powers of x where chi(), f() are Ramanujan theta functions.

Original entry on oeis.org

1, -1, 0, 0, 0, -1, -2, 2, 1, 0, 0, 2, 0, 0, -2, 0, 1, 0, 0, 0, 0, -1, -2, 0, 2, -2, 0, 2, 0, -2, 0, 0, 2, -1, 0, 0, 0, 0, 0, 2, 3, 0, 0, 0, 0, -2, -2, 0, 0, 0, 0, 0, 0, 0, -2, 2, 1, -2, 0, 2, 0, 0, -4, 0, 2, -1, 0, 0, 0, 0, -2, 2, 0, 0, 0, 2, 0, 0, 0, 0, 2
Offset: 0

Views

Author

Michael Somos, Jun 09 2015

Keywords

Comments

Ramanujan theta functions: f(q) (see A121373), phi(q) (A000122), psi(q) (A010054), chi(q) (A000700).

Examples

			G.f. = 1 - x - x^5 - 2*x^6 + 2*x^7 + x^8 + 2*x^11 - 2*x^14 + x^16 - x^21 + ...
G.f. = q - q^4 - q^16 - 2*q^19 + 2*q^22 + q^25 + 2*q^34 - 2*q^43 + q^49 + ...

Links

Crossrefs

Cf. A082564, A129134, A255318, A255319, A257398.

Programs

  • Mathematica
    a[ n_] := SeriesCoefficient[ QPochhammer[ x, x^2] QPochhammer[ -x^3] QPochhammer[ x^6], {x, 0, n}];
a[ n_] := If[ n < 0, 0, (-1)^Quotient[ 3 n, 2] DivisorSum[ 3 n + 1, KroneckerSymbol[-2, #] &]];
  • PARI
    {a(n) = my(A); if( n<0, 0, A = x * O(x^n); polcoeff( eta(x + A) * eta(x^6 + A)^4 / (eta(x^2 + A) * eta(x^3 + A) * eta(x^12 + A)), n))};
  • PARI
    {a(n) = if( n<0, 0, (-1)^(3*n\2) * sumdiv(3*n + 1, d, kronecker( -2, d)))};

Formula

Expansion of q^(-1/3) * eta(q) * eta(q^6)^4 / (eta(q^2) * eta(q^3) * eta(q^12)) in powers of q.
Euler transform of period 12 sequence [ -1, 0, 0, 0, -1, -3, -1, 0, 0, 0, -1, -2, ...].
G.f.: Product_{k>0} (1 + x^(3*k)) * (1 - x^(6*k))^2 / ( (1 + x^k) * (1 + x^(6*k)) ).
-2 * a(n) = A082564(3*n + 1). a(n) = A129134(3*n + 1).
a(4*n + 3) = 2 * A257402(n-1). a(8*n) = A257398(n). a(8*n + 2) = a(8*n + 4) = a(16*n + 3) = a(16*n + 15) = 0. a(16*n + 7) = 2 * A255318(n). a(16*n + 11) = 2 * A255319(n).

A258764 Expansion of chi(-x^2) * psi(-x^3)^2 in powers of x where psi(), chi() are Ramanujan theta functions.

Original entry on oeis.org

1, 0, -1, -2, 0, 2, 0, 0, 0, 0, -1, 0, 2, 2, -2, 0, 1, 0, 0, -2, 0, 0, -2, 0, 0, 0, 0, -2, 2, 2, 0, 0, 1, 0, 0, -2, 0, 2, 0, 0, 0, 0, -1, -2, 2, 2, 0, 0, 2, 0, -2, 0, 0, 0, -2, 0, 0, 0, -2, -2, 0, 0, 0, 0, 2, 0, -1, 0, 0, 4, 0, 0, 0, 0, 0, -2, 0, 2, -2, 0, 3
Offset: 0

Views

Author

Michael Somos, Jun 09 2015

Keywords

Comments

Ramanujan theta functions: f(q) (see A121373), phi(q) (A000122), psi(q) (A010054), chi(q) (A000700).

Examples

			G.f. = 1 - x^2 - 2*x^3 + 2*x^5 - x^10 + 2*x^12 + 2*x^13 - 2*x^14 + x^16 + ...
G.f. = q^2 - q^8 - 2*q^11 + 2*q^17 - q^32 + 2*q^38 + 2*q^41 - 2*q^44 + ...

Links

Crossrefs

Cf. A082564, A129134, A255317, A255318, A255319, A257399, A257402.

Programs

  • Mathematica
    a[ n_] := SeriesCoefficient[ QPochhammer[ x^2, x^4] QPochhammer[ x^3]^2 / QPochhammer[ x^6, x^12]^2, {x, 0, n}];
a[ n_] := If[ n < 0, 0, (-1)^Quotient[ n, 2] DivisorSum[ 3 n + 2, KroneckerSymbol[-2, #] &]];
  • PARI
    {a(n) = my(A); if( n<0, 0, A = x * O(x^n); polcoeff( eta(x^2 + A) * eta(x^3 + A)^2 * eta(x^12 + A)^2 / (eta(x^4 + A) * eta(x^6 + A)^2), n))};
  • PARI
    {a(n) = if( n<0, 0, (-1)^(n\2) * sumdiv(3*n + 2, d, kronecker( -2, d)))};

Formula

Expansion of q^(-2/3) * eta(q^2) * eta(q^3)^2 * eta(q^12)^2 / (eta(q^4) * eta(q^6)^2) in powers of q.
Euler transform of period 12 sequence [ 0, -1, -2, 0, 0, -1, 0, 0, -2, -1, 0, -2, ...].
G.f.: Product_{k>0} (1 + x^(2*k)) * (1 - x^(3*k))^2 * (1 - x^(2*k) + x^(4*k))^2.
a(n) = A129134(3*n + 2). -2 * a(n) = A082564(3*n + 2).
a(4*n) = A257399(n). a(8*n + 3) = -2 * A255318(n). a(8*n + 5) = 2 * A255319(n). a(8*n + 6) = -2 * A257402(n-1). a(16*n) = A257398(n). a(16*n + 2) = - A257399(n). a(16*n + 12) = 2 * A255317(n).
a(8*n + 1) = a(8*n + 7) = a(16*n + 4) = a(16*n + 8) = 0.

A255320 Expansion of chi(-x) * psi(x^3) * psi(x^48) in powers of x where chi(), psi() are Ramanujan theta functions.

Original entry on oeis.org

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

Views

Author

Michael Somos, Feb 21 2015

Keywords

Comments

Ramanujan theta functions: f(q) (see A121373), phi(q) (A000122), psi(q) (A010054), chi(q) (A000700).

Examples

			G.f. = 1 - x - x^5 + x^8 + x^16 - x^21 - x^33 + x^40 + x^48 - x^49 + ...
G.f. = q^19 - q^22 - q^34 + q^43 + q^67 - q^82 - q^118 + q^139 + q^163 + ...

Links

Crossrefs

Cf. A227395, A255317, A255318, A255319, A256574.

Programs

  • Mathematica
    a[ n_] := SeriesCoefficient[ QPochhammer[ x, x^2] EllipticTheta[ 2, 0, x^(3/2)] EllipticTheta[2, 0, x^(24)] / (4 x^(51/8)), {x, 0, n}];
  • PARI
    {a(n) = my(A); if( n<0, 0, A = x * O(x^n); polcoeff( eta(x + A) * eta(x^6 + A)^2 * eta(x^96 + A)^2 / (eta(x^2 + A) * eta(x^3 + A) * eta(x^48 + A)), n))};
  • PARI
    {a(n) = my(A, p, e); if( n<0 || n%8 == 2, 0, A = factor(3*n + 19); 1/2 * prod( k=1, matsize(A)[1], [p, e] = A[k, ]; if( p<5, -(p+e==3), p%8 > 4, 1-e%2, e+1)))}; /* Michael Somos, Apr 24 2015 */

Formula

Expansion of q^(-19/3) * eta(q) * eta(q^6)^2 * eta(q^96)^2 / (eta(q^2) * eta(q^3) * eta(q^48)) in powers of q.
Euler transform of a period 96 sequence.
a(4*n + 2) = a(4*n + 3) = a(8*n + 4) = a(16*n + 9) = a(16*n + 13) = 0.
-2 * a(n) = A227395(3*n + 19). a(8*n) = A255317(n). a(16*n + 1) = -A255318(n). a(16*n + 5) = -A255319(n).
a(n) = (-1)^n * A256574(n). - Michael Somos, Apr 24 2015
Showing 1-6 of 6 results.

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