65641

Appears in sequences

• Strong pseudoprimes to base 42.at n=21A020268
• Expansion of (1-x)*(1+x)/(1-2*x-x^2+x^3).at n=14A052534
• Numbers n such that sigma_3(n) is divisible by square of cototient of n, while n is not a prime number.at n=25A091286
• a(n) = 2a(n-1) + a(n-2) - a(n-3); a(0)=4, a(1)=9, a(2)=20.at n=12A109110
• Composite numbers k for which k - phi(k) divides k-1.at n=18A160599
• Numbers of the form k^3+k^2+k+1 that are the product of two distinct primes.at n=6A176070
• Let i be in {1,2,3}, let r >= 0 be an integer and n=2*r+i-1. Then a(n)=a(2*r+i-1) gives the quantity of H_(7,2,0) tiles in a subdivided H_(7,i,r) tile after linear scaling by the factor x^r, where x=sqrt((2*cos(Pi/7))^2-1).at n=31A187069
• Replace 3^i with n^i in ternary representation of n.at n=39A193760
• Numbers n such that n^2 + 1, (n+1)^2 + 1 and (n+2)^2 + 1 are divisible by a square.at n=9A218048
• a(n) = (40^n - 1)/39.at n=4A218743
• Semiprimes of the form n^3 + n^2 + n + 1.at n=7A237627
• The least common multiple of 1+n and 1+n^2.at n=40A281660