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This work, besides its fundamental interest, is motivated by the astrophysical importance of formaldehyde. For example formaldehyde was detected by millimeter techniques in Orion-KL and in several low-mass protostars }} {\textbf{526}} 845-53 (1999)}. However, no line parameters are presently available in the spectroscopic databases for the rotational transitions within the 2$\mathrm{<mrow\; data-mjx-texclass="ORD">1</mrow>}$, 3$\mathrm{<mrow\; data-mjx-texclass="ORD">1</mrow>}$, 4$\mathrm{<mrow\; data-mjx-texclass="ORD">1</mrow>}$ and 6$\mathrm{<mrow\; data-mjx-texclass="ORD">1</mrow>}$ first excited vibrational states of formaldehyde. The goal of this study is to generate a list of line parameters for these "hot" transitions in order to help such - may be - future identifications in astrophysical spectra. For this reason, submillimeter spectra were recorded at Lille and at Koln in the 150-650 and 850-900 GHz spectral ranges, respectively. These sub millimeter data were combined in a least squares fit calculation with the infrared experimental data available in the literature for the $\nu 3$, $\nu 4$ and $\nu 6$ bands }} {\textbf91}, 646 (1989)}, and for the $\nu 2$ band }} {\textbf{245}}, 141-144, (2007)}. The Hamiltonian model accounts for the various Coriolis-type resonances which perturb the energy levels of the 3$\mathrm{<mrow\; data-mjx-texclass="ORD">1</mrow>}$, 4$\mathrm{<mrow\; data-mjx-texclass="ORD">1</mrow>}$ and 6$\mathrm{<mrow\; data-mjx-texclass="ORD">1</mrow>}$ vibrational states. In addition a weaker and somehow unexpected anharmonic resonance coupling the 2$\mathrm{<mrow\; data-mjx-texclass="ORD">1</mrow>}$ and 3$\mathrm{<mrow\; data-mjx-texclass="ORD">1</mrow>}$ energy levels was accounted for.Using this theoretical model, it proved possible to reproduce satisfactorily the experimental data and to generate a list of line positions and intensities for the $\nu 2 \leftrightarrow \nu 2$, $\nu 3 \leftrightarrow \nu 3$, $\nu 4 \leftrightarrow \nu 4$, and $\nu 6 \leftrightarrow \nu 6$ rotational transitions.