Properties

Label 16.4.a
Level $16$
Weight $4$
Character orbit 16.a
Rep. character $\chi_{16}(1,\cdot)$
Character field $\Q$
Dimension $1$
Newform subspaces $1$
Sturm bound $8$
Trace bound $0$

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Defining parameters

Level: \( N \) \(=\) \( 16 = 2^{4} \)
Weight: \( k \) \(=\) \( 4 \)
Character orbit: \([\chi]\) \(=\) 16.a (trivial)
Character field: \(\Q\)
Newform subspaces: \( 1 \)
Sturm bound: \(8\)
Trace bound: \(0\)

Dimensions

The following table gives the dimensions of various subspaces of \(M_{4}(\Gamma_0(16))\).

Total New Old
Modular forms 9 2 7
Cusp forms 3 1 2
Eisenstein series 6 1 5

The following table gives the dimensions of the cuspidal new subspaces with specified eigenvalues for the Atkin-Lehner operators and the Fricke involution.

\(2\)Dim.
\(+\)\(1\)

Trace form

\( q + 4q^{3} - 2q^{5} - 24q^{7} - 11q^{9} + O(q^{10}) \) \( q + 4q^{3} - 2q^{5} - 24q^{7} - 11q^{9} + 44q^{11} + 22q^{13} - 8q^{15} + 50q^{17} - 44q^{19} - 96q^{21} + 56q^{23} - 121q^{25} - 152q^{27} + 198q^{29} + 160q^{31} + 176q^{33} + 48q^{35} - 162q^{37} + 88q^{39} - 198q^{41} - 52q^{43} + 22q^{45} - 528q^{47} + 233q^{49} + 200q^{51} - 242q^{53} - 88q^{55} - 176q^{57} + 668q^{59} + 550q^{61} + 264q^{63} - 44q^{65} - 188q^{67} + 224q^{69} - 728q^{71} + 154q^{73} - 484q^{75} - 1056q^{77} + 656q^{79} - 311q^{81} - 236q^{83} - 100q^{85} + 792q^{87} + 714q^{89} - 528q^{91} + 640q^{93} + 88q^{95} - 478q^{97} - 484q^{99} + O(q^{100}) \)

Decomposition of \(S_{4}^{\mathrm{new}}(\Gamma_0(16))\) into newform subspaces

Label Dim. \(A\) Field CM Traces A-L signs $q$-expansion
\(a_2\) \(a_3\) \(a_5\) \(a_7\) 2
16.4.a.a \(1\) \(0.944\) \(\Q\) None \(0\) \(4\) \(-2\) \(-24\) \(+\) \(q+4q^{3}-2q^{5}-24q^{7}-11q^{9}+44q^{11}+\cdots\)

Decomposition of \(S_{4}^{\mathrm{old}}(\Gamma_0(16))\) into lower level spaces

\( S_{4}^{\mathrm{old}}(\Gamma_0(16)) \cong \) \(S_{4}^{\mathrm{new}}(\Gamma_0(8))\)\(^{\oplus 2}\)