20773
domain: N
Properties
Primality
- Prime
- yes
Appears in sequences
- Numbers k such that the period of the continued fraction for sqrt(k) contains exactly 98 ones.at n=19A031866
- Sums of 7 distinct powers of 3.at n=41A038469
- Bessel function Y_0(n) is a monotonically decreasing positive sequence.at n=37A046961
- Revert transform of 2*x*(1 - x - x^3 - x^5)-x/(1+x).at n=8A049177
- Average of four successive primes squared, (prime(n)^2 + prime(n+1)^2 + prime(n+2)^2 + prime(n+3)^2)/4, n>=2.at n=31A075894
- Number of primes between 3^n and 4^n.at n=8A076959
- Twin-prime-indexed primes (TWIPS): members of a pair of twin primes whose prime index is also a member of a pair of twin primes.at n=41A087373
- Prime(prime(n)) when prime(prime(n)) and n are twin primes.at n=18A087394
- Scale factor by which primitive Pythagorean triangle {x=A088509(n), y=A088510(n), z=A088511(n)} needs be enlarged in order to circumscribe the smallest integral square having a side on the hypotenuse.at n=22A088544
- n^4 + n-th prime.at n=11A089621
- Ulam's spiral (WNW spoke).at n=36A143859
- Number of walks within N^3 (the first octant of Z^3) starting at (0,0,0) and consisting of n steps taken from {(-1, -1, 0), (-1, 0, -1), (-1, 1, 1), (1, -1, 0), (1, 0, 0)}.at n=10A148269
- Numbers of the form prime(prime(prime(k))) with a digit sum which is prime.at n=34A162252
- Take A163498(n) written in binary, insert a 0 before every 1. a(n) is the decimal equivalent of the result.at n=39A163499
- The number of different classes of 2-dimensional convex lattice polytopes having volume n/2 up to unimodular equivalence.at n=42A187015
- Primes which are the arithmetic mean of the squares of four consecutive primes.at n=7A234364
- Lengths of runs of the initial digits of semiprimes in decimal representation, cf. A239634.at n=42A239639
- Prime numbers that have a triangular Voronoi cell in the Voronoi diagram of the Ulam prime spiral.at n=36A257527
- Primes p = x^2 + y^2 such that x - y is a cube greater than one.at n=25A282405
- Triangle read by rows: Polynomial coefficients per comment.at n=40A290053