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prog.sf
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prog.sf
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#!/usr/bin/ruby
# Number of distinct prime factors of (p[1]*...*p[n])+(p[n+1]*...*p[2n]), where p[n] is the n-th prime.
# https://oeis.org/A093429
# a(n) = A001221(A002110(n) + A002110(2*n) / A002110(n)). - ~~~~
# Terms a(1)-a(54):
# 1, 1, 1, 1, 2, 2, 2, 3, 2, 3, 2, 2, 3, 2, 2, 4, 3, 2, 6, 3, 4, 4, 3, 1, 1, 3, 3, 3, 3, 2, 4, 3, 3, 3, 3, 5, 4, 2, 3, 3, 5, 3, 7, 4, 1, 4, 3, 4, 3, 6, 2, 4, 3, 3
include("../../../factordb/auto.sf")
func a(n) {
pn_primorial(2*n)/pn_primorial(n) + pn_primorial(n)
}
#for k in (1 .. 1e6) {
for k in (54 .. 1e6) {
var u = pn_primorial(2*k)
var t = pn_primorial(k)
var m = (u/t + t)
#print(omega(m), ", ")
say [k, omega(m)]
}
__END__
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