The sequence 1, 31, 331, 3331, 33331, ... (OEIS A033175) consisting of , 1, ... 3s followed by a 1 has its
th term given by
The result is prime for , 2, 3, 4, 5, 6, 7, 17, 39, ... (OEIS A055520);
i.e., for 31, 331, 3331, 33331, 333331, 3333331, 33333331, ... (OEIS A051200,
with its initial term 3 omitted), a fact which Gardner (1997) calls "a remarkable
pattern that is entirely accidental and leads nowhere."
) and the only positive
integer which is the sum of the factorials of the
preceding positive integers (
). It is also the first odd
prime. A quantity taken to the power 3 is said to be
cubed.
, 1, ... 3s followed by a 1 has its
th term given by
, 2, 3, 4, 5, 6, 7, 17, 39, ... (OEIS A055520);
i.e., for 31, 331, 3331, 33331, 333331, 3333331, 33333331, ... (OEIS A051200,
with its initial term 3 omitted), a fact which Gardner (1997) calls "a remarkable
pattern that is entirely accidental and leads nowhere."
