21751

Properties

Appears in sequences

• Convolution of natural numbers with Beatty sequence for tau^2 A001950.at n=35A023542
• Partial sums of A000009 (partitions into distinct parts).at n=47A036469
• Numerators of continued fraction convergents to sqrt(857).at n=9A042654
• Prime lucky numbers k (from A031157) such that nextprime(k)=nextlucky(k).at n=29A057698
• Primes of the form k^2 - 7*k + 7.at n=30A089376
• Smallest prime such that n*k(n)^2+n*k(n)+1 is a prime > (n-1)*k(n-1)^2+(n-1)*k(n-1)+1 with k(n)>1 or 0 if n=4 as no prime possible.at n=24A104995
• Primes p such that p-1 and p+1 each contain at least one cubed prime in their prime factorization.at n=32A162870
• Primes of the form 250n + 1.at n=23A179231
• The Gi1 and Gi2 sums of Losanitsch's triangle A034851.at n=35A192928
• Expansion of g.f. (1-2*x+51*x^2)/(1-x)^3.at n=30A257352
• The x member of the positive proper fundamental solution (x = x1(n), y = y1(n)) of the first class for the Pell equation x^2 - D(n)*y^2 = +8 for odd D(n) = A263012(n).at n=35A264349
• Primes p such that 2*p+1 is divisible by the sum of digits of p+1.at n=34A267542
• a(1) = 2; a(n + 1) = smallest prime > a(n) such that a(n + 1) - a(n) is the product of 7 primes.at n=37A285692
• Numbers k such that (16*10^k + 167)/3 is prime.at n=20A294227
• Lucky primes k such that k+6 is also a lucky prime.at n=32A309381
• Indices at which record high values occur in A326344.at n=30A326298
• Number of partitions of 2n that describe the degree sequence of exactly one labeled multigraph with no loops.at n=36A328863
• G.f. A(x) satisfies A(x) = 1 / ((1 - x) * (1 - x * A(x^3))).at n=20A367691
• a(n) = Sum_{i=1..A328404(n)} (A276086(n) mod prime(i))*A002110(i-1), where A276086 is the primorial base exp-function, and A328404(n) gives the length of A276086(n) in primorial base representation.at n=28A391936
• Prime numbersat n=2440