A006304 -id:A006304 - cp's OEIS frontend

A006306 Coefficients of the '2nd-order' mock theta function mu(q).

1, -1, 1, 2, -1, -4, 1, 5, -2, -5, 4, 7, -4, -11, 3, 13, -6, -14, 9, 18, -7, -24, 8, 29, -14, -32, 17, 38, -18, -50, 20, 58, -25, -63, 33, 77, -35, -94, 36, 108, -48, -122, 60, 141, -63, -170, 70, 195, -87, -215, 101, 250, -110, -294, 124, 333, -146, -371, 173, 424, -190, -492, 206, 554, -245, -617, 283

Offset: 0

N. J. A. Sloane

Contribution from Jeremy Lovejoy, Dec 19 2008: (Start)
Coefficients of the "second-order" mock theta function mu(q).
|a(n)| is the number of partitions of n without repeated odd parts whose M2-rank is even minus the number of partitions of n without repeated odd parts whose M2-rank is odd. (End)

			G.f. = 1 - x + x^2 + 2*x^3 - x^4 - 4*x^5 + x^6 + x*x^7 - 2*x^8 - 5*x^9 + ...

N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence).

T. D. Noe, Table of n, a(n) for n = 0..1000
G. E. Andrews, Mordell integrals and Ramanujan's "Lost" Notebook, pp. 10-48 of Analytic Number Theory (Philadelphia 1980), Lect. Notes Math. 899 (1981).
K. Bringmann, K. Ono and R. Rhoades, Eulerian series as modular forms, J. Amer. Math. Soc. 21 (2008), 1085-1104. [From _Jeremy Lovejoy_, Dec 19 2008]
J. Lovejoy and R. Osburn, M_2-rank differences for partitions without repeated odd parts [From _Jeremy Lovejoy_, Dec 19 2008]
R. J. McIntosh, Second order mock theta functions, Canad. Math. Bull. 50 (2007), 284-290. [From _Jeremy Lovejoy_, Dec 19 2008]

Cf. A006304, A006305.

CoefficientList[Series[Sum[(-q)^n^2 Product[(1-q^(2k-1))/(1+q^(2k))^2, {k, 1, n}], {n, 0, 10}], {q, 0, 100}], q]
a[ n_] := If[ n < 0, 0, SeriesCoefficient[ Sum[ (-1)^k x^k^2 QPochhammer[ x, x^2, k] / QPochhammer[- x^2, x^2, k]^2, {k, 0, Sqrt[ n]}], {x, 0, n}]]; (* Michael Somos, Jul 09 2015 *)

G.f.: Sum_{n >= 0} (-1)^n q^n^2 (1-q)(1-q^3)...(1-q^(2n-1))/((1+q^2)^2 (1+q^4)^2 ... (1+q^(2n))^2).

Corrected and extended by Dean Hickerson, Dec 13 1999

A006305 Taylor series related to one in Ramanujan's Lost Notebook.

Original entry on oeis.org

1, 2, 4, 6, 10, 16, 25, 38, 58, 84, 122, 174, 244, 338, 465, 630, 850, 1136, 1508, 1988, 2608, 3398, 4408, 5688, 7306, 9342, 11900, 15090, 19070, 24008, 30122, 37666, 46955, 58348, 72302, 89338, 110094, 135316, 165912, 202924, 247632, 301508

Offset: 0

N. J. A. Sloane

			G.f. = 1 + 2*x + 4*x^2 + 6*x^3 + 10*x^4 + 16*x^5 + 25*x^6 + 38*x^7 + 58*x^8 + ...

N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence).

Vaclav Kotesovec, Table of n, a(n) for n = 0..20000
G. E. Andrews, Mordell integrals and Ramanujan's "Lost" Notebook, pp. 10-48 of Analytic Number Theory (Philadelphia 1980), Lect. Notes Math. 899 (1981).

Cf. A006304, A006306.

Series[Sum[q^(n^2+n)/(1-q)^2 Product[(1+q^(2k))/((1-q^(2k))(1-q^(2k+1))^2), {k, 1, n}], {n, 0, 9}], {q, 0, 100}]
a[ n_] := If[ n < 0, 0, SeriesCoefficient[ Sum[ x^(k k + k) QPochhammer[ -x^2, x^2, k] / (QPochhammer[ x, x, 2 k + 1] QPochhammer[ x, x^2, k + 1] ) , {k, 0, Sqrt @ n}], {x, 0, n}]]; (* Michael Somos, Jul 09 2015 *)
nmax = 100; CoefficientList[Series[Sum[x^(k^2+k)/(1-x)^2 * Product[(1+x^(2*j))/((1-x^(2*j))*(1-x^(2*j+1))^2), {j, 1, k}], {k, 0, Floor[Sqrt[nmax]]}], {x, 0, nmax}], x] (* Vaclav Kotesovec, Jun 11 2019 *)

G.f.: Sum_{n>=0} q^(n^2+n) (1+q^2)(1+q^4)...(1+q^(2n))/((1-q)^2 (1-q^2) (1-q^3)^2 (1-q^4) ... (1-q^(2n)) (1-q^(2n+1))^2).

a(n) ~ c * exp(r*sqrt(n)) / n^(3/4), where r = 2.74858241446108527... and c = 0.1051685561271293027... - Vaclav Kotesovec, Jun 12 2019

Corrected and extended by Dean Hickerson, Dec 13 1999

A153140 Coefficients of the second order mock theta function B(q).

Original entry on oeis.org

1, 2, 4, 6, 9, 14, 20, 28, 40, 54, 72, 98, 129, 168, 220, 282, 360, 460, 580, 728, 912, 1134, 1404, 1734, 2129, 2604, 3180, 3864, 4680, 5658, 6812, 8182, 9808, 11718, 13968, 16618, 19720, 23350, 27600, 32550, 38313

Offset: 0

Jeremy Lovejoy, Dec 19 2008

nonn

Vaclav Kotesovec, Table of n, a(n) for n = 0..10000
R. J. McIntosh, Second order mock theta functions, Canad. Math. Bull. 50 (2007), 284-290.

Other '2nd order' mock theta functions are at A006304, A006306.

nmax = 100; CoefficientList[Series[Sum[x^(k^2+k) * Product[(1+x^(2*j))/(1-x^(2*j+1))^2, {j, 0, k}], {k, 0, Floor[Sqrt[nmax]]}]/2, {x, 0, nmax}], x] (* Vaclav Kotesovec, Jun 12 2019 *)

lista(nn) = my(q = qq + O(qq^nn)); gf = sum(n = 0, nn, q^n * prod(k = 1, n, 1 + q^(2*k-1)) / prod(k = 0, n, 1 - q^(2*k+1))); Vec(gf) \\ Michel Marcus, Jun 18 2013

G.f.: Sum_{n >= 0} q^(n^2+n)(1+q^2)(1+q^4)...(1+q^(2n))/(1-q)^2(1-q^3)^2...(1-q^(2n+1))^2.
G.f.: Sum_{n >= 0} q^n(1+q)(1+q^3)...(1+q^(2n-1))/(1-q)(1-q^3)...(1-q^(2n+1)).
a(n) ~ exp(Pi*sqrt(n/2)) / (2^(5/2) * sqrt(n)). - Vaclav Kotesovec, Jun 12 2019

More terms from Michel Marcus, Jun 18 2013

cp's OEIS Frontend

A006306 Coefficients of the '2nd-order' mock theta function mu(q).

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A006305 Taylor series related to one in Ramanujan's Lost Notebook.

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A153140 Coefficients of the second order mock theta function B(q).

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