81689

Properties

Appears in sequences

• A list of equal temperaments (equal divisions of the octave) whose nearest scale steps are closer and closer approximations to the ratios of six simple musical tones: 8/7 5/4 4/3 3/2 8/5 7/4.at n=48A060526
• G.f. A(x) satisfies: 1/(1 + x) = A(x)*A(x^2)^2*A(x^3)^3*A(x^4)^4* ... *A(x^k)^k* ...at n=44A307657
• First of four consecutive primes p,q,r,s such that the sum of numerator and denominator of p/q + q/r, p/q + r/s, and q/r + r/s, are all prime.at n=20A355696
• Prime numbersat n=7990