Nonrelativistic-energy<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mi>Z</mml:mi></mml:math>-expansion coefficients for singly excited<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mi>S</mml:mi></mml:math>and<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mi>P</mml:mi></mml:math>states of two-electron ions

Coefficients ${E}_{k}$ in the $Z$-expansion series for $E(Z)$, where $E(Z)$ is the nonrelativistic total energy and $Z$ the nuclear charge, are tabulated for singly excited $n(^{1,3}S)$ and $n(^{1,3}P)$ states of two-electron ions, $n=2\ensuremath{-}5$. These results were obtained largely from an analysis of variational $E(Z)$ values given by Accad, Pekeris, and Schiff but were taken in some cases from variational-perturbation calculations of other authors. The $Z$-expansion estimates of nonrelativistic term values for ions with $Z\ensuremath{\ge}11$ have been compared with the corresponding results of Ermolaev and Jones, and agreement within 1 or 2 parts in ${10}^{7}$ was found for most states.