Created
January 16, 2026 16:54
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Compute number of primes of form x^2 + x + A for x <= 10^11 (for Jacobson and Williams A = 3399714628553118047)
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| export(A=3399714628553118047); a(n)=parsum(k=0, 10^n, isprime(k^2+k+A)); | |
| default(threadsizemax,1000*10^6); \\ default 8MB was too small | |
| # | |
| print(a(11)); |
Author
Author
Michael J. Jacobson, Jr.,
Computational techniques in quadratic fields,
Master’s thesis, University of Manitoba, Winnipeg, Manitoba, 1995.
Michael J. Jacobson Jr. and Hugh C. Williams,
New Quadratic Polynomials With High Densities Of Prime Values,
Math. Comp., 72, 241, 499-519, 2002.
Number of primes of the form x^2 + x + A for x <= 10^n, with A=3399714628553118047 from Jacobson:
n a(n)
-- -----------
0 1
1 5
2 24
3 235
4 2482
5 25034
6 251841
7 2517022
8 25153819
9 251014697
10 2408242218
11 22066543923
a(11) is 1.61412× bigger than a(11) for A=41 (Euler polynomial primes),
and 5.35848× bigger than number of "normal" primes up to 10¹¹.
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Started on 192C/384T Lenovo x3950-X6 8-socket server with Intel Xeon 8890v4 CPUs with
this was longest such computation for x≤10¹¹ sequences mostly from oeis.org sofar.
a(11)=22066543923 was computed in 27:10h real time, and 215.55 days total time: