30361

Appears in sequences

• Strong pseudoprimes to base 43.at n=19A020269
• Strong pseudoprimes to base 98.at n=28A020324
• Number of ordered triples (a, b, c) with gcd(a, b, c) = 1 and 1 <= {a, b, c} <= n.at n=32A071778
• Numbers k such that sigma(k+1) divides sigma(k-1).at n=35A227304
• The first of five consecutive positive integers the sum of the squares of which is equal to the sum of the squares of six consecutive positive integers.at n=2A262017
• Partial sums of the number of active (ON, black) cells in n-th stage of growth of two-dimensional cellular automaton defined by "Rule 195", based on the 5-celled von Neumann neighborhood.at n=36A270691
• a(n) = (n+3)*Sum_{i=0..n} binomial(3*n-2*i+2,n-i)/(2*n-i+3).at n=6A277957
• For any n > 0, if A006666(n) >= 0, then a(n) = Sum_{i = 0..A006666(n)-1} 2^i * [T^i(n) == 0 (mod 2)] (where [] is an Iverson bracket and T^i denotes the i-th iterate of the Collatz function A014682); otherwise a(n) = -1.at n=37A304715
• a(n) = s(n,n) + s(n,n-1) + s(n,n-2), where s(n,k) are the unsigned Stirling numbers of the first kind (see A132393).at n=22A308305