https://agupubs.onlinelibrary.wiley.com/doi/10.1002/2016GL071930
Etminan, M., G. Myhre, E. J. Highwood, and K. P. Shine (2016), Radiative forcing of carbon dioxide, methane, and nitrous oxide: A significant revision of the methane radiative forcing, Geophys. Res. Lett., 43, 12,614–12,623, doi:10.1002/2016GL071930.


N̅ = 334 ppb N2O (for date ranges centered on 2023)
  ref: https://www.researchgate.net/figure/Atmospheric-N2O-concentration-trend-from-the-combined-Global-Monitoring-Division-data-set_fig4_337479379


CO2:
  RF = [a₁⋅(C-C₀)² + b₁⋅(C-C₀) + c₁⋅N̅ + 5.36] × ln(C-C₀)

where:
  C₀ = starting CO2 level (ppmv CO2)
  C = ending CO2 level
  (C-C₀) = change in CO2 level
  a₁ = -2.4E-7 W/m² per ppmv CO2
  b₁ = 7.2E-4 W/m² per ppmv CO2
  c₁ = -2.1E-4 W/m² per ppbv N2O


Assuming C₀=280 [circa 1780] and C=560 [one doubling] ...
  (C-C₀) = 280 ppmv CO2

  a₁⋅(C-C₀)² = -2.4E-7 × 280² = -0.018816
    https://www.google.com/search?q=-2.4E-7+%C3%97+280%C2%B2+%3D

  b₁⋅(C-C₀) = 7.2E-4 × 280 = 0.2016 
    https://www.google.com/search?q=7.2E-4+%C3%97+280+%3D

  c₁⋅N̅ = -2.1E-4 × 334 = -0.07014
    https://www.google.com/search?q=-2.1E-4+%C3%97+334+%3D

  RF = [a₁⋅(C-C₀)² + b₁⋅(C-C₀) + c₁⋅N + 5.36] × ln(C-C₀)
     = [-0.018816 + 0.2016 + -0.07014 + 5.36] × ln(C-C₀)
     = 5.472644 × ln(C-C₀)


Assuming C₀=350 [circa 1987] and C=490 ...
  (C-C₀) = 140 ppmv CO2

  a₁⋅(C-C₀)² = -2.4E-7 × 140² = -0.004704
    https://www.google.com/search?q=-2.4E-7+%C3%97+140%C2%B2+%3D

  b₁⋅(C-C₀) = 7.2E-4 × 140 = 0.1008
    https://www.google.com/search?q=7.2E-4+%C3%97+140+%3D

  c₁⋅N̅ = -2.1E-4 × 334 = -0.07014
    https://www.google.com/search?q=-2.1E-4+%C3%97+334+%3D

  RF = [a₁⋅(C-C₀)² + b₁⋅(C-C₀) + c₁⋅N + 5.36] × ln(C-C₀)
     = [-0.004704 + 0.1008 + -0.07014 + 5.36] × ln(C-C₀)
     = 5.385956 × ln(C-C₀)


Assuming C₀=400 [circa 2015] and C=440 ...
  (C-C₀) = 40 ppmv CO2

  a₁⋅(C-C₀)² = -2.4E-7 × 40² = -0.000384
    https://www.google.com/search?q=-2.4E-7+%C3%97+40%C2%B2+%3D

  b₁⋅(C-C₀) = 7.2E-4 × 40 = 0.0288
    https://www.google.com/search?q=7.2E-4+%C3%97+40+%3D

  c₁⋅N̅ = -2.1E-4 × 334 = -0.07014
    https://www.google.com/search?q=-2.1E-4+%C3%97+334+%3D

  RF = [a₁⋅(C-C₀)² + b₁⋅(C-C₀) + c₁⋅N + 5.36] × ln(C-C₀)
     = [-0.000384 + 0.0288 + -0.07014 + 5.36] × ln(C-C₀)
     = 5.318276 × ln(C-C₀)


Assuming C₀=350 [circa 1987] and C=420 [2023] ...
  (C-C₀) = 70 ppmv CO2
  N̅ = 320 ppbv N2O

  a₁⋅(C-C₀)² = -2.4E-7 × 70² = -0.001176
  https://www.google.com/search?q=-2.4E-7+%C3%97+70%C2%B2+%3D

  b₁⋅(C-C₀) = 7.2E-4 × 70 = 0.0504
  https://www.google.com/search?q=7.2E-4+%C3%97+70+%3D

  c₁⋅N̅ = -2.1E-4 × 320 = -0.0672
  https://www.google.com/search?q=-2.1E-4+%C3%97+320+%3D

  RF = [a₁⋅(C-C₀)² + b₁⋅(C-C₀) + c₁⋅N + 5.36] × ln(C-C₀)
     = [-0.001176 + 0.0504 + -0.0672 + 5.36] × ln(C-C₀)
     = 5.342024 × ln(C-C₀)