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Dimension of the space of weight 2n cusp forms for Gamma_0( 21 ).
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%I #10 Aug 22 2019 12:18:12

%S 1,6,12,16,22,28,32,38,44,48,54,60,64,70,76,80,86,92,96,102,108,112,

%T 118,124,128,134,140,144,150,156,160,166,172,176,182,188,192,198,204,

%U 208,214,220,224,230,236,240,246,252,256,262

%N Dimension of the space of weight 2n cusp forms for Gamma_0( 21 ).

%H William A. Stein, <a href="http://wstein.org/Tables/dimskg0n.gp">Dimensions of the spaces S_k(Gamma_0(N))</a>.

%H William A. Stein, <a href="http://wstein.org/Tables/">The modular forms database</a>

%F Conjectures from _Colin Barker_, Jun 09 2019: (Start)

%F G.f.: x*(1 + x)*(1 + 4*x + 2*x^2 + x^3) / ((1 - x)^2*(1 + x + x^2)).

%F a(n) = a(n-1) + a(n-3) - a(n-4) for n>5.

%F (End)

%K nonn

%O 1,2

%A _N. J. A. Sloane_, Jul 08 2001