Saturday, October 22, 2022

[vfnebgfb] primorial exp

according to Wikipedia, n# ~= e^n , which is neat.

we calculate an approximation of e by computing (2^22)# = 4194304# , a 1820662-digit number, then take its 2^22th root:

? s=1; n=22; forprime(p=1,2^n,s*=p); for(i=1,n,s=sqrt(s)); s

time = 25,123 ms.

2.7169361789139649491006308820480538380

(this is a terribly inefficient way of calculating e.)

although n# ~= exp(n), or log(n#) ~= n, what are the next terms of the asymptotic expansions, analogous to Stirling's approximation to factorial?

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