Given the high precision and speed of the PIPs approach, it is also important to "push" PIPs to even larger molecules, as well as more complex datasets. We report that here in the first of a series of papers devoted to alkanes C n H 2n+2 . In this paper the focus is on C 14 H 30 . We present a large and complex dataset of DFT/B3LYP energies and gradients for this 44-atom hydrocarbon. Then we use our fragmented basis approach to fit this dataset along with a novel, many-body PIPs approach that is inspired by previous MB PIPs methods. Although this paper focuses on the methods to generate the dataset and the fits to it, we go beyond the usual precision metrics by presenting extensive results from molecular dynamics calculations, geometry optimizations and normal-mode analysis.