prog.sf

#!/usr/bin/ruby

# Numbers n such that 2^n + 3^n is a semiprime.
# https://oeis.org/A050244
# a(34) > 23194.

for k in (23194..1e6) {

    say "Testing: #{k}"

    if (is_semiprime(3**k + 2**k)) {
        die "Found: #{k}"
    }
}

# Numbers m such that 4^m - m is a semiprime.
# https://oeis.org/A252657
# Next term >= 483                  -- http://factordb.com/index.php?id=1100000000251223208

# Numbers m such that 10^m - m is a semiprime.
# https://oeis.org/A252663
# 107, 117, 143, 149, 177,

# Numbers m such that m*10^m + 1 is a semiprime.
# https://oeis.org/A216378
# 111, 117, 123, 181, 184, 187,

# Numbers k such that 1 + (product of first k primes) is a semiprime.
# https://oeis.org/A085725
# 76,

# Numbers n such that 3^n-2 is a semiprime.
# https://oeis.org/A080892
# Next term >= 658                  -- http://factordb.com/index.php?id=1000000000018245962

# Numbers n such that Pell(n) is a semiprime.
# https://oeis.org/A250292
# Next term >= 709                   -- http://factordb.com/index.php?id=1100000000707746051