Sylvester's Sequence - Closed Form Formula and Asymptotics

Closed Form Formula and Asymptotics

The Sylvester numbers grow doubly exponentially as a function of n. Specifically, it can be shown that

for a number E that is approximately 1.264084735305302. This formula has the effect of the following algorithm:

s0 is the nearest integer to E2; s1 is the nearest integer to E4; s2 is the nearest integer to E8; for sn, take E2, square it n more times, and take the nearest integer.

This would only be a practical algorithm if we had a better way of calculating E to the requisite number of places than calculating sn and taking its repeated square root.

The double-exponential growth of the Sylvester sequence is unsurprising if one compares it to the sequence of Fermat numbers Fn; the Fermat numbers are usually defined by a doubly exponential formula, but they can also be defined by a product formula very similar to that defining Sylvester's sequence:

Read more about this topic:  Sylvester's Sequence

Famous quotes containing the words closed, form and/or formula:

    “Night hath closed all in her cloak,
    Twinkling stars love-thoughts provoke,
    Danger hence good care doth keep,
    Jealousy itself doth sleep;”
    —Sir Philip Sidney (1554–1586)

    “Every idea is endowed of itself with immortal life, like a human being. All created form, even that which is created by man, is immortal. For form is independent of matter: molecules do not constitute form.”
    —Charles Baudelaire (1821–1867)

    “Beauty, like all other qualities presented to human experience, is relative; and the definition of it becomes unmeaning and useless in proportion to its abstractness. To define beauty not in the most abstract, but in the most concrete terms possible, not to find a universal formula for it, but the formula which expresses most adequately this or that special manifestation of it, is the aim of the true student of aesthetics.”
    —Walter Pater (1839–1894)