term-by-term sum = 1.5961632439130233 using 20 terms
term-by-term sum = 1.5759958390005426 using 13 terms
exact value = 1.6449340668482264
accelerated sum = 1.6449340669228176 using 13 terms
estimated error = 0.0000000000888360
actual error = 0.0000000000745912