30889

Appears in sequences

• Pseudoprimes to base 15.at n=35A020143
• Strong pseudoprimes to base 18.at n=19A020244
• Strong pseudoprimes to base 33.at n=13A020259
• Strong pseudoprimes to base 52.at n=16A020278
• a(n) = (2*n+1)*(10*n+1).at n=39A033574
• Number of partitions satisfying 0 < cn(1,5) + cn(2,5) + cn(3,5) and 0 < cn(4,5) + cn(2,5) + cn(3,5).at n=39A039901
• Composite numbers m such that phi(m)*sigma(m) is divisible by m-1.at n=37A065149
• Composite numbers k which divide A001045(k-1).at n=32A066488
• Composite numbers k such that k divides F(k-1) where F(j) are the Fibonacci numbers.at n=12A069106
• Sarrus numbers n (A001567) which satisfy mu(n) = -1 and which are not Super-Poulet numbers (A050217).at n=20A074380
• Sarrus numbers with more than 2 distinct prime factors.at n=23A080747
• Odd Fibonacci pseudoprimes: odd composite numbers k such that either (1) k divides Fibonacci(k-1) if k == +-1 (mod 5) or (2) k divides Fibonacci(k+1) if k == +-2 (mod 5).at n=21A081264
• For p = prime(n), a(n) is the smallest base-2 pseudoprime N (that is, 2^(N-1) = 1 mod N) such that p divides N.at n=20A085999
• Numbers k that divide Fibonacci(k-1) but do not divide Fibonacci(k) - 1.at n=7A094410
• Sum of three edges of box having both integral orthogonal sides and integral geodesic distances between opposite vertices.at n=4A095257
• Sarrus numbers A001567 that are not Carmichael numbers A002997.at n=31A153508
• Composite numbers n with the property that phi(n) divides (n-1)^2.at n=11A173703
• Nonprimes k such that 9*k divides 2^(k-1) - 1.at n=30A175521
• Pseudoprimes to base 2 of the form 4k+1.at n=34A178723
• Records for minima of the positive distance d between the ninth power of a positive integer x and the square of an integer y such that d = x^9 - y^2 (x <> k^2 and y <> k^9).at n=5A179790