Duluth Road Cyclists: 5; FIVE; CINCO; CINQ; FUNF; FEM

OK . . . so this post was going to be about

and how when Steve rides with us we have to raise our game

Instead it will be about

Tim, and the number

for those of you unfamiliar with this symbol, it is a "number"

For those of you with limited time,
or interest you may wish to skip this part
(Five is between 4 and 6 and is the third prime number. Because it can be written as 2^2¹+1, five is classified as aFermat prime. 5 is the third Sophie Germain prime, the first safe prime, the third Catalan number, and the thirdMersenne prime exponent. Five is the first Wilson prime and the third factorial prime, also an alternating factorial. Five is the first good prime. It is an Eisenstein prime with no imaginary part and real part of the form $3 n - 1$ . It is also the only number that is part of more than one pair of twin primes. Five is a congruent number. Five is conjectured to be the only odd untouchable number and if this is the case then five will be the only odd prime number that is not the base of an aliquot tree.

The number 5 is the 5th Fibonacci number, being 2 plus 3. 5 is also a Pell number and a Markov number, appearing in solutions to the Markov Diophantine equation: (1, 2, 5), (1, 5, 13), (2, 5, 29), (5, 13, 194), (5, 29, 433), ... lists Markov numbers that appear in solutions where one of the other two terms is 5). Whereas 5 is unique in the Fibonacci sequence, in the Perrin sequence 5 is both the fifth and sixth Perrin numbers.
5 and 6 form a Ruth–Aaron pair under either definition. The classification however may be frowned upon.
There are five solutions to Znám's problem of length 6.
Five is the second Sierpinski number of the first kind, and can be written as S2=(2²)+1
While polynomial equations of degree 4 and below can be solved with radicals, equations of degree 5 and higher cannot generally be so solved. This is the Abel–Ruffini theorem. This is related to the fact that the symmetric group S_nis a solvable group for n ≤ 4 and not solvable for n ≥ 5.
While all graphs with 4 or fewer vertices are planar, there exists a graph with 5 vertices which is not planar: K₅, thecomplete graph with 5 vertices.
Five is also the number of Platonic solids.
A polygon with five sides is a pentagon. Figurate numbers representing pentagons (including five) are calledpentagonal numbers. Five is also a square pyramidal number.
Five is the only prime number to end in the digit 5, because all other numbers written with a 5 in the ones-place under the decimal system are multiples of five. As a consequence of this, 5 is in base 10 a 1-automorphic number.
Vulgar fractions with 5 or 2 in the denominator do not yield infinite decimal expansions unlike expansions with most prime denominators, because they are prime factors of ten, the base. When written in the decimal system, all multiples of 5 will end in either 5 or 0.

We rode fast into a gorgeous sunrise over the lake